Im trying my hand ant a RPG also.
I had to make a silly 3d shooter before I had most of the key elements for an RPG type game.
Im still at the no media level but a lot of media has been pre fabbed since i ported once to DBP lost 5000 lines! and had to rewrite it again
If i was to make any game
Id study these aspects as they are in most games.
Handling variables and media is a large
excercise to go through but is a key ingrediant
Timers timing time timed events
collision with distance calculations
arrays and advanced array concepts
saving arrays
TYPES with arrays
The rest is methodical problem solving required for the specifics of your game idea.
good luck
do start small tho, even if the first fighting game is just 2 sprites shooting at each other like in a 2d western scene with cactii and spinnerfex.
it cant hurt to base your research on the game type u want to finally make.
practise makes perfect in the long run
http://www.lunarpixel.com/ is my new site