I was told I use use too many commas so I've been scouting about for some punctuation/writing guides. I found this one http://lightnovel.jpn.org/study/punctuation.html which seems pretty helpful. Does anyone else have any other suggestions?

Thanks for the link. I've wondered about that more than once too. I generally try and avoid commas unless it makes reading confusing (nested clauses, too much hiragana etc), but I doubt that's a very accurate way to do it. I wonder if there are any books on the subject. I've seen more than one of English punctuation, but I imagine that's a bit more complicated than its Japanese equivalent.