Never limp it UTG unless you got a good reason. A good reason is a laggy psycho at your table that likes to reraise a bunch, and you definitely wanna reraise/shove that one preflop.
Other than that, raise 3-5xbb, don't fold to 3bet, unless you are certain villain only 3bets AA and KK. Postflop you can do bunch of stuff, but if you don't have many reads, fold to any aggressor that wants to stake you for all your chips (unless you hit a set ofc )