It depends on table conditions. I deviate from this, but my basic 6-max strategy is:

UTG/MP raise 22-AA, ATs+, KQs, AJ+
depending on table conditions I sometimes loosen up and mix in some QJs, JTs, sometimes smaller SCs.

CO/Button additionaly to UTG/MP I raise suited aces/connectors/one gappers and broadways. A9+

good standart preflop raise is 4 x BB + 1BB for each additional limper.