First convert as many splines to arcs as possible. Then use the ARC FILTER settings in the tool path for that particular tool. This has worked wonders for me over the years.

You will definitely learn a lot by trial and error. Start by programming a part and then going to the machine, set up the job and run it yourself. This way you will see what you are doing right and just as importantly you will see what you are doing wrong. Also order some books, probably start with Mill level one. Progress to creating solids, then Mill Level 3. If you work all the way through the examples given in the books you will start to learn shortcuts. But the end result is the same for all of us, needing good code to make quality parts. And don't expect to learn it overnight, it will take a little bit of time, frustration, and patience. Also this forum is a very good source of information as I have been reading posts here for the past two years. You never know when you might pick up that one tidbit of information you need. Good luck.