80 lb; good for finished drawings, pencil, colored pencil, inks and markers.  It is more forgiving than sketchbook paper for graphite drawings - erases easier and cleaner.  Typically an ivory color.  Comes as pad or as 18x24 single sheets.

100 lb; basically a very heavyweight paper, good for pencil, colored pencil, inks, markers, and also can be used for watercolor (it will buckle if lots of water is used).  Can be difficult to erase.  Comes as pad or as 18x24 single sheets.

140 lb; usually the textured surface will discourage use for anything but watercolor, but good for mixed media pieces.  Many different types - experiment to find what you prefer.  Comes as pad or as 20x30 single sheets.

similar to cardboard, but with a smooth drawing surface; can handle just about anything from pencil to acrylic and oil paintings if properly treated.  Great for mixed media pieces.  Comes in 30x40 sheets.

I use a mechanical pencil for drawing, mostly because I'm used to it.  I would sneak mechanical pencils from my dad when I was 12 to draw with, and I've used them ever since.  They don't need to be sharpened (which is what I like), they don't get that nasty dry, hard eraser like ordinary pencils, some of them have very narrow erasers that are great when you just want to erase small areas, and they are convenient and neater than ordinary pencils.  A down side, however, is that you can't get them in different softnesses and they do have a limited value range (which I have discovered).  So, also have some drawing pencils on hand for additional shading.  I'd suggest a hard pencil, like a 2h or 3h, a medium pencil, like a hb, and a soft pencil, like a 2b or 3b.  If you use wood pencils, make sure you have a good sharpener. 

I recently bought a set of Derwent graphic/sketching pencils and I am very happy with them.  If you're wondering if the brand of pencil makes a difference, it does.  Like most other art supplies, buy the best you can afford.

If you are going to be doing finished drawings with lots of shading, it is good idea to get some fixative to prevent smearing.

If you use pencils, you gotta have a good eraser.  If you don't know about kneaded rubber erasers, I suggest you march yourself to the closest art store and get one as soon as possible.  Kneaded rubber erasers come as a small, grey rectangle, but once you start playing with them they become pliable, and rather like a lump of silly putty.  You can shape them to fit the area you are erasing, and you can simply press them over a area to lighten it, instead of erasing it entirely.  They also don't leave those nasty eraser shreds on your paper.  They are wonderful for erasing graphite smudges that occur when you're working on a drawing.  They kick ass.  I prefer the Design 2 brand, myself.  Just make sure you keep them off the floor.  They can collect hair and dirt, and they are a pain to get out of the carpet once they have been stepped on.

Some people swear by those plastic clickable erasers that can be refilled.  I haven't used them personally, but I can see how they would be neat.

A white vinyl eraser is nice to have for erasing large areas very cleanly.

When I first started inking I used micron pigma pens.  They are $3 - $4 apiece, and they come in lots of different widths, from .005 to .5.  They are very portable and convenient, and they give good results.  The nibs of the pens are fairly delicate, and once they wear down the lines can be difficult to control.  They also seem to run out of ink fairly quickly, and they are expensive to replace often.

I have switched to dip pens, which I prefer.  Dip pens aren't nearly as convenient as the micron pigma pens.  You need to have a fairly stable workspace, with fresh water, paper towels, scratch paper, and no one to bump you.  However, for $12 you can get a set of nibs, nib holders, and a bottle of ink that will easily last you many, many drawings.  Dip pens will give you a more natural, responsive line.  Different nibs will give a varying line width and respond differently to pressure.  Once you find a favorite nib or two, you won't want to go back to the stiff, unnatural micron pens.  I suggest the drawing and sketching package by Speedball - it gives you 2 nib holders and 6-8 different nibs to try, all for about $8.  Remember to clean your nibs after each use, and don't leave them in water - they rust.  Be prepared to replace nibs every once in a while for $1 or so.

Another reason to use dip pens is the choice of ink available.  There is calligraphy ink, waterproof ink, india ink, metallic inks and a huge spectrum of colored inks available, just to name a few.  Whatever ink you use, make sure it is colorfast.  A bottle of white ink is handy for covering up mistakes.  You can get a bottle of ink for $3 - $4, enough for many, many drawings.

Dip pens are messy.  Ink can get spilled.  Pets and ink are a bad combination.  Ink and carpet is a bad combination.  Make sure that you eliminate any spilling risks before you start.

A selection of fine brushes is also useful for inking, especially for going over large areas.  Try inking over a finished pencil piece, or just ink alone.  Use it as a base for colored work.  The possibilities are endless.

Waterproof ink:

Be sure the bottle says waterproof.  Once you let this dry you can use watercolor, colored inks or markers to color it without having the black ink leak all over the place.  There usually is still a little bit of leakage, especially with markers, but not enough to be really noticeable.  Be careful not to get this on your clothes, 'cause it will leave a grey stain even if you wash the ink out promptly.
Colored inks:
Using brown ink or some other color for linework underneath watercolor is actually a pretty good idea.  Pick a neutral color, or one that will blend with the color next to it.  The effect is less stark than using black ink and more natural.  Be sure to spray the ink with fixative before applying watercolor or ink, because most colored inks are not waterproof and will get muddled.

If you want good markers, go with Prismacolors.  They are simply the best.  They are also expensive.  :-(  If you want to try them out, try getting a selection of cool greys to play with.  They are available singly, or in sets.  Either way, be prepared to pay about $3 apiece.  The cool grey set that I love is about $36.  I've found that if you want a set of colors, try an office supply store like Office Depot or Office Max.  Their prices are sometimes lower than art stores.

The markers can bleed through sketchbook paper, so make sure you have blank paper underneath the drawing you are coloring.

I got the 120 color set of Prismacolor pencils for a birthday a while ago, and I have yet to do anything decent with them.  Very sad.  I know people can do wonderful things with Prismacolor pencils, but I have yet to turn out anything.  :-(  Probably because I haven't been practicing with them.  I prefer a harder lead pencil, like Verithin, because my style is cross-hatched based and I like to layer lots of colors.  Prismacolors are a bit frustrating for me to work with.

Brushes:

Buy a few good brushes rather than a handful of cheap ones.  You will have better control over your brushstrokes and you won't be as likely to put color where you don't want it.  Windsor Newton makes some great brushes.  The University line (red handles with white fibers) is priced for the student, but lasts a long time.  I, err, "borrowed" a University brush from my art class, still have it 6 years later and use it often.  If you take care of them they will last you quite a while.  Don't leave brushes standing in water - the tips will bend.  Clean them with a little soapy water in the palm of your hand every once in a while.  Don't let paint dry on them.  Don't let your little sister steal them and use them for fabric paints.  Frankly, speaking from experience, don't let anyone besides you touch them because they will probably ruin them.

Oddly enough, it's not necessary to buy dinky fine brushes for detail if you have good regular brushes.  I prefer to use my #2 round for detail rather than some much smaller cheap-o brushes I have, because the #2 has a much better tip.

Again, my experience with this media is limited.  For some artists, the price of watercolor paper is a bit of a deterrent (it was for me for a while).  Using watercolor on regular paper is a bad idea.  Bristol is a cheaper alternative, though it isn't as nice as watercolor paper and you have to be careful not to saturate the paper - good for ink/watercolor combinations, though.

The watercolors themselves can be fairly inexpensive - you're likely to spend more on brushes.  Sets can run from $5 up to $20 or more.  Don't buy the cheap school brand - you probably won't be happy with the results.  Watercolors can come in a liquid or a cake format.  I haven't used the liquids, but one of the nice things about watercolors is even if you leave some of the liquid color out and it completely dries, it is still usable if you add a little water.  Try to find a set with a good bright red - most of the watercolor reds are really dark pink masquerading as red and you'll have to mix colors (adding brown helps) to get a good true red.

Get good brushes.  Nothing is more frustrating than trying to use watercolor with bad brushes.

A plastic palette is a good thing to have, since you can't mix watercolors on a paper palate.  And DO mix colors!  If you use them straight from the cake or tube, you are missing all the great nuances of color you can only get through mixing.  Have an extra piece of paper ready to test colors before you put them on your painting.  Try to stay away from using black when mixing.  Use brown, blue or purple to darken.

I have just recently bought some acrylic paints and all the paraphernalia to go with them, but as I have yet to really get any experience with them I guess this section will have to wait.  Needless to say, they're a lot more expensive to work with than any media I've tried so far, and that makes them difficult to pick up for young artists who doesn't have $200 to spend on brushes, pallets, canvases or illustration board, medium, gesso, etc.