My go-to strategy is peace through superior industry. Outproduce everyone and you can field fleets that will make nobody want to touch you. 
Especially the early game is critical here and I find that a somewhat common mistake some players make is to grab every resource they see. Focus on high-yield resources and on grabbing the tech for upgraded energy and minerals producing buildings. With those two things in mind, you can start snowballing a little earlier than other empires and really put a decent distance between yourself and AIs by mid-game.
Especially the early game is critical here and I find that a somewhat common mistake some players make is to grab every resource they see. Focus on high-yield resources and on grabbing the tech for upgraded energy and minerals producing buildings. With those two things in mind, you can start snowballing a little earlier than other empires and really put a decent distance between yourself and AIs by mid-game.