Welcome to hoop-la la land, the place where the rubber meets the road and get rubber melted all over it. No, it only looks like tar.
First thing is read the instructions for all the tools you use. A glancing look is OK until you got a question. Like that Abrams guy on "the yankee workshop" be sure to use the safety equipment, lol. Make adjustments to get things working right. Wait! GIMP and my Wacom Graphire2 won't play nice. I've got to dig deeper into that, I'll "Google" for help. In the meantime, my old Wacom does play well with MyPaint. For Inkscape the mouse is less stress. Hey, it's how I roll, you find what works for you.
My first desire is to not do finished art, but to be able to sketch ideas the same as I've done it in my notebooks. Pictorial notes, storyboarding, sketching, they become a mental bookmark. When I review my sketches often I remember everything I thought about concerning the sketch, including the mood I was in, music associations if I was really into it. I even get a rush of desire as if the original inspiration were present. I can then pick up where I left off. I also save ideas to reuse them and combine them with other ideas, hybrids are all the rage.
Well I mainly use Inkscape because vector drawing is similar to CAD programs like AutoCad. Check out LibreCad, I did and It's cool. Bit-map or raster drawing makes me feel like a traditional artist. My cursor is not constrained. This freehand sketching loosens you up.
For precision tightness you need pen practice. Check out this site http://clippingimages.blog.com/2010/06/20/graphic-tablet-exercises/ Now this is a tute by "Dusty Ghost" who's web site is down. The exercises will help you get a grip on your pen and mouse. Thanks to the folk on Clipping Images. Another inspirational and instructional site belongs to David Revoy http://www.davidrevoy.com/tutoriel.html ....he is awesome, dig deep, he's got some serious help for open source artist. And park your cursor over at http://linuxgraphicsusers.com/forum/ because we are drowning in the Adobe suite world and the little nation of open source artist needs an oasis, the forum is cool. No offense Adobe fans, what ever tools you have at is cool wid me!
OK, you got the hardware, the software, the gall, the time and the motive, all you need is the effort. Ain't nuttin to it but to do it. OOOh! There is this open source app called Tux Paint for kids. Don't let the kid thing fool you. It's got a few tricks of it's own and in the hands of a smart-aleck, unkid like magic can be made, lol, my grandkids hooked me up.