I limp a lot less than I used to, but I still do it from time to time. I try not to do it when there are a few thinking players at the table because of how exploitable it is, but if the table is mostly fish (it almost always is), limping isn't that horrible.
Sometimes I'll do it with suited connectors or small-medium pairs, and if it gets raised, I'll call if the pot is multiway. IMO, it is a good way to set mine against poor players. You avoid getting 3bet off a small pair and instead can call a standard raise with good implied odds
, and poor players generally don't even think about and/or exploit your limp range.
Don't limp with anything you're not willing to call a standard raise with, though. Limp/folding is like throwing money away. If you did it five times per hour throughout an eight hour session, that is an $80 difference at the end of the day. Big leak.
Also, don't fall into the trap of adjusting your bet sizing to the strength of your hand for the sake of not limping. I'll see players who usually raise to $12 preflop suddenly raise to $5 one hand. It's usually a dead giveaway that they have a small-medium pair or something like 10-9s. If you're going to raise, raise as if you have a premium.