I try to avoid "flammable" clothes - fleeces and the like, and often use a nomex growbag, for all the usual good reasons.
For summer, I have a homemade thin Nomex flying jacket - all I did was cut the legs off an old RAF flying suit, replace the zip and hem it. Scruffy as heck, but comfortable and very well equipped with pockets. And, of-course, flame retardent.
Stout shoes, for all the obvious good reasons.
I find a headset bag useful - they zip up, and will take all of the "fod" items from my pockets: keys, wallets, pens, etc. A simple and painless pre-flight precaution.
Thin leather gloves I wear most aeroplanes, most of the time (unless it's open cockpit and I'm wearing much thicker gloves anyhow).
G