i do tricking/XMA and manage to do backflips, BHS, frontflips, wallflips, aerials and that stuff. world's best tutorials are on
http://www.trickstutorials.com
edit: just be sure you also read the general advices on tricking, like flexibility and that stuff. it is really important - maybe not for easy flips, but if you don't want to hurt yourself lateron, you should probably read it ^^
and my experience was... i dunno - try. crash. try with spotter. crash. try. crash. try it on solid floor. crash. try. and so on
frontflip: just train
backflip: if you are afraid of backflipping, use a spotter (= a friend who helps you during the jump, e.g. by turning you over). if you want to know something about a specific trick, just ask here ^^
self teaching and your own experience will only break your back.
some of the world's greatest artist have taught themselves all the moves... there are lots of understandable tutorial videos for the easier moves. of course, if you want to do some tricks on concrete floor, improve your landing. for this, i also recommend a trainer
plus, training with some friends really brings some benifits with it.. more fun, you can help each other. and if you're advanced, maybe try a tricking workshop