I'm about halfway through this book these guys mentioned above, and while some lessons/exercises are pretty cool and efficient, there are others that just don't work for me. I still do them, but deep inside I'm thinking "Jesus... it looks better when I try my own methods." I'm in a weird position though. Recently I decided that I wanted to learn how to draw too, except... I used to draw and paint every day for hours, but I quit around 2004 because I became addicted to two things that I regret today since I essentially ruined my career when I was getting started. So I wasted a whole decade and I no longer have my own style, everything looks like shit, the stuff I make today looks worse than what I did 10 years ago. At least I think so, I don't know for sure because I trashed all my work years ago. I guess this is some advice already? Don't ruin your own life?
But yeah, it sounds cliche but the honest advice is practice. Start drawing something you're comfortable with, but also try things that you just know you're terrible at. Spend hours drawing everyday. At first it will look like shit, don't let people tell you otherwise because most people can't be honest when you ask them for their opinion. The honest answer is "no, man, that's garbage" but they'll say how amazing it is. This is good to keep you motivated, but you have to be honest with yourself.
Hearing only good things doesn't do you any good and you'll risk getting lazy because hey, everyone keeps telling you you're so good. Try and get some constructive criticism out of people who know what they're doing. A mere "omg amazing!!1" from your aunt does nothing. Don't be afraid to make mistakes, don't try to get your lines right the first time around, sketch a lot, don't rush things thinking you can finish a drawing in 5 minutes, etc. Some very talented people/pros put up videos on Youtube so maybe you could learn something simply by watching how they do it.
Please note that just because your drawing looks terrible, it doesn't mean you can't be happy with it. It's all about getting some perspective on things. I just drew my own hand recently and while it's undeniably flawed, I was happy with it because I haven't done anything in a decade.