If you're really having a problem with it, why don't you try easing into it a little slower. First, like it's been suggested, try getting an inexpensive tartan kilt like Stillwater. Then try going to a few Scottish/Irish/Celtic Festivals where others will also be kilted to build up your confidence in a friendly environment. Then start wearing it on special days, like St. Patrick's Day or National Tartan Day. All of these will help build up your confidence and get others used to seeing you kilted. Then just start wearing it on other days.

There will always be some people who look at you funny, and sometimes you may get some derogatory remarks. But the only way to get used to wearing the kilt is to wear it. I think everyone here will admit that wearing the kilt is doing something outside the societal norm, so you just have to accept that. The trick is to get comfortable being outside the norm.