Basicly, draw, Draw again, and keep drawing.
The web is full of free tutorials and people giving more advice than you'll ever have time to go through, watch and learn when you're not drawing, just don't push it to a point where you're procrastinating too much from drawing by watching videos, or fooling yourself into thinking you can get good without practice.
Challenge yourself.
For instance, get an idea for a picture, define your idea, and then try to draw what you defined, without letting the lines and you own limitations change your goal.
It's a good way to force yourself out of your comfort zone, and learn to do new stuff.
It's probably gonna look below the standard of what you do inside your confort zone, but don't be discouraged by that. If you're unsatisfied with the result, start over and do it again. Draw untill your goal is reached, or untill you reach a point where you find it easier to start over towards the same goal.
Keep your old versions so you can see your progress, as that is very motivational, add a date-note to your pictures as well, month/year is enough, as notable progress doesn't happen that much from day to day.
Don't limit yourself to the same subjects either.
Do drawings of objects, interriors, exterriors, people, and anything else you can come up with.
Do line-art, value art, colored art.
Try out different styles.
Don't try to do everything at once, in the same picture. When you plan a piece, define what you wanna do.
For instance "a line-drawing of a dragon in flight" maybe with a specific style determined.
Don't be afraid of copying other peoples work, you can learn a lot from that. (by drawing an existing picture, Copy/pasting a picture off the web into photoshop won't teach you much

)
Find somewhere to get quallified critique, leave your ego behind, and cherish it for what it's worth, critique is essential to artistic development.
You could use deviantart, elfwood or some other art-site for that, if you don't know anyone IRL who can do it for you, heck you could even start a thread here on the escapist for it.
Just make sure to be aware of your source when recieving critique. Praise from someone with no skill or knowledge is hardly a guarantee that your work is good, especially not if it's your family/friends as they're usually over-encouraging.
Online, people who don't know what they're talking about have an oppinion as well, and likes to share it.
learn to dissect whats usefull from what's not, this applies to the internet as a whole, not just art critique.
Study anatomy.
Understanding realistic anatomy will help you not only with realism, but with charicature, stylized anatomy etc.
Animation: "The Animators Survival Kit" is considered the bible in animation. If you're going that way, get that book, and start putting on your analythical/observant glasses whenever you're watching people.
If you want a career in animation, learning 3d animation will expand your job options enormously.
The jump from 2D to 3D animation isn't that much work, most skilled 3D animators are former 2D animators.
Untill you go professional, the process is more important than the product.
If you wanna go pro, learning to work digitally is a big plus.
Photoshop and a wacom tablet is your essential tools. You can substitute photoshop for GIMP if you don't like pirating software.
Ctrl-Z is a feature that really needs to get implemended IRL.
Try posting some of your drawings here, in this thread, preferably edited into the OP, people will get an idea of where you are.