The best way to get started is to be one of two things - rather controlled, or rather not.
Then just draw, draw, draw, draw......
Personally, I recommend working with pencil and colored pencil on printer paper, doing between 8 and 12 illustrations on the side of a page. This will work your control and they are too tiny for anyone to obsess over, which is probably where a sense of failure comes from.
Aternatively, you can buy one of those big newsprint pads and some charcoal and do fast drawings, one or two to a page side, and keep yourself to about 20 minutes. If you go over, you are thinking too hard. The purpose is to make drawing a natural thing, where you don't feel as though your life depends on every move you make. Breaking past that uncertainty is the first step to learning.
As far as subject matter, pick random shit, and pick things that you can see. A flashlight, a pair of shorts, your watsebasket. Why? Because none of these things will ever really matter. A scribbled coaster is not going to redifine you as a person. Your left shoe turned on end is not a pietà. You are expecting a lot for someone who is just 16; even if you were michelangelo or picasso you would have at least 5 years before you needed to change the world.
Be content to sketch, and, upon sketching, say, "This is a fine sketch, much better than before. Next time, I should accomplish even more."
Be aware of your practise and how it shows in your work. If you are not improving, try something different. Talent is a measure of how rapidly you are able to progress, inspiration a measure of one's ability to have ideas, while skill is a measure of the effort you put in. The most uninspired, talentless individual can still have skill (see
thomas kinkade).