[Cerlin]

I use trade agreements, which are pretty straight forward.

Also mutual attack agreements which are not in fact an alliance. It is just an agreement to attack the same person. These generally lead to good feeling between the players and an informal style alliance but nothing cement set in agreements. In two of my last games I had arrangements like this which worked out pretty well.

There are also the Offensive/defensive alliances. I generally pick one or both. But sometimes your interest is only keeping them alive and not attacking you, not helping them expand. Depends on situation really...