I tend to stay away from the Scottish looking kilt pins. I choose kilt pins based on me or my interests. Maple Leaf, a small hammer, a coil of gold rope. I resently picked up what is considered a brooch on EBay (cheap and unique scource of kilt pins) that will compliment a tartan that I just ordered.

However be warned a sword kilt pin is mojo. My first kilt pin was a sword and I got a lot of interest from the ladies when first kilted. One day I lent it to a fellow kiltie (for the interest of public safety Improv1 shall not be named - Yes I'm looking at you, Dick of Canboro, in southern Ontario.). Bam he starts getting all the interest and since that time nary a friggin kilt check! I don't like Dick anymore, he stole my mojo and won't give it back!

For kilt pins there are no rules, no conventions. Have fun with it wear something that compliments you. Illigitimus Non Carborundum, Dude.