One key to poker is making the right counter-plays.  There are a lot of
plays in poker that are wrong, but only if the opponents make the right
counter-plays.  If they don't, then the play becomes a good one.

A) limping a lot trying to make good hands.  Counter-play by making big
raises with good hands to make limping wrong.

B) bluffing a lot.  Counter-play by calling or re-raising with good
hands.

C) playing very tight.  Counter-play by bluffing at them more.

The key here that I'm talking about is that these ways of playing are
not strictly wrong (unlike playing too loose, which is basically just
wrong).  These plays are actually *right* if the opposition is not
making the correct counter-plays.

For example, case A, if the opposition is never raising preflop, letting
you limp, then you should limp a lot.  Try to make big flops.  Of course
you should still be smart about it, you need the right implied odds; you
want to play hands that can make the nuts or very nearly the nuts and take all their chips
(in no limit).