Its true when you look at trickers most aren't that concerned about there form, but what you also have to take into account is the ammount of tricks we can learn, the tricktionary is stacked with over 260 tricks and thats not all the tricks possible. Gymnastics, well tumbling comes down to round offs, carts, back tucks x1-x3, fronts x1-x3, back fulls ect... Our moves are more diverse in nature, from kicks *martial arts*, backs *gymnastics*, flairs *breaking*, and corks a combination of all three. Its true, maybe us as trickers should spend more time perfecting our technique, but there is no one who is "perfect" in the sence that theres a standard for our tricks. Sure we have to land them, and make them look correct, but gymnastics have a whole formula for grading something as simple as a back tuck. Thats what differentiates us from gymnasts *tumblers*.
They might seem very similar but infact are quite different, so enough about gymnasts and trickers. The best thing you can do is be a tricker, and go to a gym facility lol yet that isn't mandatory. I've started basically on grass *yet im still at a 540* but thats all you really need, for more risky tricks just get a friend, as I'm sure Russell has said before.
Just take it to the grass, warm up, get a friend and progress through the moves...Don't throw a cork, if you can't do btwist, don't throw a btwist if you can't do a bkick, and don't throw a bkick if you can't kick *exept aussies =P, jks!* Once you get the basics down, harder moves won't seem as hard...Take it slow and at your own pace..
Oh and after a day of trying to do front flips, my abs KILLED!!! Its normal, tricking works a lot of different muscle groups, some you've never really worked before. It'll take awhile but it won't be as sever, just make sure you let your body recover between sessions.