Its really quite simple.
Firsrt you learn everything you can. Never stop learning. There is ALWAYS something new to learn. Than you make every mistake in the book. Than learn from those mistakes and try not to make the same mistake twice. Most importantly, when you make a mistake - you own up to it.
If you follow these rules exactly you will be a really good paralegal. As the years pass the more mistakes you make, the better a paralegal you will become.
Its all about being there and having done that.