2dogs- Marbles and aquarium beads are good goals but yeah, a tough thing to start with LOL
Asiceloff- We've ALL been there, done that, promise!
Keep playing and look at the process and learning how to shape and how glass melts. My advice is work on the shapes. Whatever else you do to the bead, if the shape is good then you can use the bead. If the shape is not so good, the bead is not useful, even if the design and colors turned out well.
Check for leaks in the torch as well, those are notorious for o-ring failures (where the head screws into the stem).
Apart from safety issues and things that don't work, like slanted mandrels or an over-reducing flame, there are not a lot of bad habits to pick up. Seriously! Everyone has their own working style, and it is whatever works for you.