Many of my artist friends have commented that they find abstract art really difficult, a bit scary even. Its mostly because they are used to painting in a more realistic fashion and find it difficult to let go of planning an outcome.
It does take a lot of practise to be able to trust in the process and allow yourself to take chances, not knowing what will happen if you splash a huge brush load of paint here or dribble some colour there.
Most of my learning has come from mistakes that turned out to look great on the canvas. I think the more abstract art you do, the more chances you take and the more you learn what looks good and what doesn't. It's definitely about taking risks and having fun and freedom!
Thats what I love about abstract painting. The fun and freedom of it. Not knowing where each painting is going. Just flowing with whatever comes forth at that particular time. It's pure freedom of expression. Yes, it is scary venturing into the unknown, but what you discover there can be enlightening and exhilerating!