What’s the most effective way to maximize skills as a character of any class?

I feel like Pathfinder skills are very compact when compared to 3.5 skills, as a result that makes each individual skill point worth more than each individual point in 3.5, due to combining some skills to form others that perform multiple functions.

Since skill points are more valuable, what are the best ways to gain as many skill points as possible as a character of any class? What’s the best way to optimize a skills modifiers for each set of classes below without affecting combat stats?

I’d prefer if the answers were formatted in the following way, explaining how each group can more easily gain skill modifiers:

  • High skill point classes: Rogue, Bard
  • Medium skill point classes: Monk, Barbarian, Alchemist
  • Low skill point classes: Fighter, Magic-users, Paladins