I'd start with asking myself, "When would I wear it?" That will give a good indication of whether you want something for partying, everyday wear, business dress, or something more formal.

That should narrow your search down to kiltmakers who make the type of kilt you want to wear.

After that you can think about features (pockets or no, plain or tartan, wash & wear or dryclean).

Keep in mind that your choice of features might affect the accessories you'll want (you'll probably want a sporran if you get a kilt without pockets, for instance).

That narrows your search even more.

Then, consider price.

It also helps to look at lots of pictures of guys in kilts and look for the styles that look good on your body type.