No real rules. Don't write "Stub" review, like "this is good game" and that's about it. Describe what's good, some parts, what you personally like... you know, so people can get some impressions even if they don't agree. Doesn't have to be long either.
As for shots, they should be 320x200, possibly png format. Use small letters for extension. Also, make sure you get one shot of title screen or anything that could serve instead of title screen.
That's about it, we are not too picky
