Let's share tactics

[PhoenixRivers]

Problem: In melee with strongly buffed caster.
Solution: Sunder spell component pouch (AC 12+dex). Bye Summon Monsters etc. Eschew Material can potentially screw this tactic.

Most casters carry 2.

Problem: Caster takes 5 ft step away from you, casts spells without provoking AoO.
One solution: Ready action to follow the wizard if he moves.

The better timing is a ready action to move adjacent to the wizard if he CASTS. Then you can get a free AoO and disrupt a spell.

Problem: Caster standing behind opponents, dealing magical death.
Solution: Bull rush the smallest opponent, then move behind the caster.

Very situational.

Problem: Ranged combat, you have a crossbow.
Solution: Drop prone, shoot and load. +4 AC, no penalties.

These were about 3.5, but all decent tactics from any system are welcomed.

The ranged one isn't really a problem.

Basics of tactics:

Movement is life. All other things equal, movement decides fights.

Action economy is the only economy.

An action that does double duty is worth more than the sum of its parts. for example: Ready action to attack if enemy casts. You damage opponent, and interfere with casting. Either is good, both together are gold.

Sometimes one action at the precise right time is better than 2 actions on your turn. Example: Ready actions. Being able to interrupt actions gives you the ability to stop your opponent before he starts.