How retro are we talking about? NES, SNES, PS1? Or handleds?
Since you want to avoid games that are a pain to play, do you prefer a game without "missables" and/or without the need of a guide? Or are you mostly talking about difficulty?
When talking about RPGs, do you only have preferences for turn based ones (Dragon Quest/Final Fantasy), or are fine with variations like more action (Mana) or strategy based (Fire Emblem)? For action adventures are you looking for something Zelda-like (more adventure) or something more "action"?