First and most important - wear what makes you comfortable (o.k. - within reason...t-shirt and boxers are very comfortable but may not be the best choice).
Two clothing choices at least...three or four is preferred. Natural, earthy tones are suggested – blues, greens, browns, creams all work well together. Avoid busy patterns, bold logos, multi-colored stripes and neon colors as these often conflict with backgrounds. White is acceptable but may not be the best choice on sunny days as it's reflects light. Props from your interests, hobbies, sports you enjoy and so forth are welcome.
Couples / Families - avoid wearing exact matches, that's so '80s (just like the green bottle of Ralph Lauren polo for men). Coordinated clothing works best. This doesn't refer to the same color necessarily, but to color 'families'. I'm happy to send you a clothing color guide as a reference.