I'd say start out small, and move upward as you get more used to wearing makeup. Start with the eyes and lips. I'll tell you about lips first since they're easier. if you have thinner lips, use a lighter skin toned or peachy colored lipstick and a light gloss. this gives the illusion of plumper lips. If you have thicker lips, go for a darker color. (not like firey red or anything... just like a darker brownish pink or something.) and a matching gloss. The lipstick gives the original color, and it works best if you put it on and then wipe it off. it sort of stains the lips so they keep the color, but they aren't as tacky. then the gloss adds shine.
for the eyes (my favorite part!)
you can choose to wear eyeshadow or not, depending on how much you want your eyes to pop. You'll probably use it later on, but to start out, it will depend on how daring you are. For eyeshadow, if you have blue eyes, I'd say go with a blue eyeshadow to bring them out. Apply darker shades to the outside corners of your eyelid, bringing it up to the crease. apply lighter colors on the rest of the lid under the crease, and a super light color (white, light skin color/creme, or blue/whatever color you're using) and sweep it on the outside, just under your brow bone in the little pouf of skin above the crease. For green eyes, follow the same routine with purple. for brown, go with earth tones. Really, you can use browns and tans for any eye color, but those are what makes your eyes pop the most.
then, eyeliner. You do eyeliner after eyeshadow because otherwise the shadow will cover it up. I always used to do this backwards... lol You can do black or brown or whatever color you want. I have a huge collection of eyeliners. (blue, dark blue, black, brown, copper, gray, gold, and purple). Eyeliner takes practice to not get it on too thick. basically, on the bottom, try to get as thin of a line as possible under the lashes. If you want your eyes to look bigger, apply a white or light colored (I use gold) liner in the waterline. On the top, try to keep it thin and even, because it will show if you don't. you can bring it out on the outside corners, but be careful and make sure both sides are the same.
Finally, mascara. I use Avon Supershock Max and will never go back. If your eyelashes are short, you can curl them and then apply mascara. You can put on several coats. (I put on like 3 and it works amazingly.)
Foundation isn't really to cover acne, and I highly recommend getting a low coverage liquid foundation and a powder. You may not use them at first, but they will come to be your good friends :) mix a little foundation and a little lotion on the back of your hand and apply it with a brush (very lightly) you'll find a little goes a long way. it evens out the skin tone and makes your skin look softer, especially if you lightly brush on some powder afterward.