It's not rocket science but there is a little more to sandblasting than selecting the blast media you use.
The blast media you use depends on what your blasting.Different media for different substrates.If your hitting foam one media if your hitting wood another media,if you doing glass etc.You might need to do some trial and error to find out what works best for you and the equip you have.
Then there is understanding resist mask technique.
Then there is understanding the equipment needed the different tips etc. for whatever media you are using and it's maintenance thereof.