I mean any of the following (my answers in green):
1. Join their war that you know you will lose and help them to the best of your ability. Defensive: Usually, unless it would basically be the end of the game for me. Offensive: Very rarely.
2. Give them provinces they want in peace deals; especially ones that you'd otherwise want. Sometimes, but rarely ones I had planned on taking at gamestart.
3. Help them put down rebellions, even when those rebellions succeeding might benefit you. Almost always, unless the ally is short term or one of circumstance.
Add anything else you do that you consider to be putting yourself out to help the AI.
1. Join their war that you know you will lose and help them to the best of your ability. Defensive: Usually, unless it would basically be the end of the game for me. Offensive: Very rarely.
2. Give them provinces they want in peace deals; especially ones that you'd otherwise want. Sometimes, but rarely ones I had planned on taking at gamestart.
3. Help them put down rebellions, even when those rebellions succeeding might benefit you. Almost always, unless the ally is short term or one of circumstance.
Add anything else you do that you consider to be putting yourself out to help the AI.