Start with basic knowledge of programming any language with oops concept. Or you can start with JS (not really oops but that's ok) since suitescript is written mainly in it.
Then do a data structure course, they are not that much required in suitescripts but your logic building will improve with it.
Then go with Suitescripting, you can get familiar with suitescript types, the NS modules later on.
I will highly recommend not to jump to step 3 directly, if you want to progress at a faster pace.. Even though skipping the first 2 steps will feel like the way to go at times.