I often steer clear of RPGM games that don't have combat, why use RPGM if you're not taking advantage of the engine? just use ren'py or unity, both are far more friendly to the player when just navigating around town.
Engrish is incredibly annoying, if i find a game has significant Engrish i just close it and never come back, i can accept some shoddy renders but not Engrish, i'm weird on that one.
If a game has underage content as a theme i'm out, same with scat, rape(as a main theme) and bestiality, not my thing at all.
Deciding if i'll play, good images help as do an interesting premise, a school sim or whatever doesn't do it for me much anymore, they aren't going to surpass superpowered or summertime saga on that front any time soon so i give it at least till 0.3 or 4 before i even think about downloading, a dev that i'm aware of helps too, frankly whatever Sin from DoD puts out next i'll look into at least once, same could be said of DrPinkCake from acting lessons.
when to replay, that's far more specific, depends on the format of the game, episodic VN's like DoD and acting lessons i play each ep, something more free form like superpowered or LLTP i generally wait three updates, or wait for a story based update, more content to explore that way and less grinding.