Basic beginner strategy tells us to follow the raise first in (RFI) charts and raise to 2.5x to 4x the BB (possibly more if the players always call), but most of the low stakes games I've played will have at least one if not more limpers by the time it gets to late position. So, how does the number of limpers affect the ranges of those basic charts? Can I follow those basic RFI ranges if there is one limper ahead? what about 2 or 3?

Also, the size of the open raise should change based on the number of limpers? I've heard that if your standard raise is 3xBB, then you should add 1xBB for each limper ahead of you. For Example, I'm on the button and three people have limped and I have a premium hand, I should raise to 6x?

I think I understand leveling the open raise amount based on number of limpers but I'm not sure how the number of limpers affects the RFI range. Also, is it EVER a good idea to limp behind?

Learn to play the game rather than following instructions by rote