There's really only one piece of advice I can give: practice relentlessly.

When I first started trying to draw seriously, I probably erased every line I put down two or three times before I was satisfied with it. Drawing is as much about muscle as it is imagination. You have to train your hand to take what's in your head and put it on the page. Drawing is like riding a bicycle; it doesn't come naturally to most people, and it's not something you're going to learn in a day.

For now, copy stuff that's what you want to draw like. Don't trace: do it by eye. Do it until you can replicate the lines and make them come out the way you want. This will take a long time.

Sketch loosely. Don't press your pencil down hard. You're inevitably going to have to erase, so make it easier for yourself.

Also, accept the fact that YOU WILL THINK YOU SUCK FOR A VERY LONG TIME. Artists are almost always the harshest critics of their work. So even when you do begin to improve, you will still look at your drawings and see only the flaws. So listen to what other people say. Accept compliments as well as critique. And if people start telling you you're getting good, let yourself believe them!