I do not really follow any tradition myself so my space is compiled of many things. I have a little bed side table that I have been using for years. It doesn't take up much space. I have a blue crystal ball, bells, my cards and runes, candles, incense, a box full of herbs and other things, and more on mine. I have known people who have used the tops of their dressers. Anything that will work.
As far as deities go that is rather personal. It all depends on what you believe and feel is right. If you are following a set tradition then there are deities in that tradition. Some have alters that honor their ancestors, some that are geared towards nature, some are seasonal, some gear them towards deities. It all depends on what you want it for.