This really depends upon the yeast you will be using. It should tell you the ideal temp range to keep the fermentation at. In my experience keeping things around 60° works well. If you go much lower than 50 you will really slow things down with the yeast. Go over 70 and you will stress the yeast and produce a much higher percent of fusel alcohols (can add a bad flavor or produce a wicked hangover). The closer to the ideal temp for the yeast, the happier it will be. Also you can reduce stress by minimizing the temperature swings and keeping things close to the same temp. Basements or closets out of drafts work well. Leaving things outside or in a garage can work but have a higher liklihood of stressing out the yeast and producing something off. Whatever you do keep good notes so you can compare for your own setup.