Limpers Suck at Poker.
A very common beginner leak is limping and cold calling too much. Remember, there are two ways to win at poker [1) show down the best hand; and 2) get everyone else to fold]. By just calling, limpers are essentially abandoning the second, more powerful method. Generally speaking, limpers, especially at the low stakes tables, are fit-or-fold poker players. They see two shiny-bright cards in their hand, and they conjure up images of making straights, flushes, and two-pair hands on the flop. They're particularly guilty of this from the blinds, where they feel they're getting a good price to limp in. The sad truth about hold'em is you only hit a flop roughly one third of the time, and a majority of those flops that technically "hit" are garbage (e.g,. bottom pair) and/or the board is scary wet. You should think of hitting the flop as just a back-up plan to your blind stealing, light 3- and 4-betting, isolating, squeezing, multi-barreling, and so on. As the pro's like to joke: No one ever hits a flop in Texas Hold'em.
All-in for now...