Well, the short answer would be no. No, you don't need a strategy guide to play Empires and Allies. The longer answer is not quite so simple though. You can play the game, and struggle along basically trying to re-invent the wheel at every turn. You can waste large amounts of time and resources as you make different attempts with varying degrees of success. That is certainly one way you can go about it.
Imagine your neighbor playing the same game. Imagine he or she grabbed up a strategy guide like Empires and Allies Domination Guide. Imagine that he or she is putting to use the communal wisdom that went into creating a guide like that in the form of the offered tips and hints while you are struggling along re-inventing the wheel. What do you think the outcome would be? Your neighbor will most likely be miles and miles ahead of you by the time you get everything he or she already knows figured out. It creates a gap that will continue to grow, and that you will likely never be able to erase.
So you have two possibilities laid out before you, and which you choose in the end is up to you and what you wish to accomplish. There isn't really a right or wrong way to go about it. For myself, I know which way I would approach the game. In fact, how I did approach the game. I picked up a copy of Empires and Allies Domination guide for myself. I read it, studied it, and put its wisdom into practice for my own empire. Now I dominate, and so can you, but the choice is yours. Pick up your copy today!