Scriptwriting courses/getting into the industry/what makes a good script?

I'm trying my hand at scriptwriting, having been a journalist, copywriter. copy editor etc. What advice can professional scriptwriters offer me on improving my writing, getting my scripts noticed (beyond the presentation - i'm good at doing good-looking documents) and having them accepted?

Do non-commissioned scripts ever see the light of day, and is there a chance that scripts without the rainbow nation garbage (you know, the desperate multi-racial socialising a la Black Label ads) will be accepted by production houses?