Pick a theme and stick within that theme. Believe it or not, placing restrictions on yourself actually helps you be more creative, as opposed to having a whole world of possibilities and no clue how to chose. For example, I'm a giant geek. I give all my beers Klngon-themed names. E.g., Bird of Prey; Black Bat'leth; Disruptor; Beer of Honor, etc. So pick a theme, something you're interested in, and name lots of beers within that theme. It's easier than just naming one. If you like cars, say all of your beers this year are going to be named after cars.
If you label your beers, that can help with the naming too. Using a sort of label template, or master design, for a particular theme basically makes your beers into a brand (even if only you and your friends are ever going to see it), and working within that "brand" restricts your choices and narrows your decision field.