synthetics/wool. wicking fabrics rock. warmer in winter/cooler in summer. some pearl shorts underneath my baggy short outer layer of choice that day. warm enough and my top is sleeveless. colder gets more layers, and wind/waterproof stuff if i'm in ugly weather.
i *alway* have a light shell jacket in my camelbak. even in summer. surprise thunderstorms can leave you very cold and wet. the shell has many times helped me be merely uncomfortable finishing a ride, rather than miserable.
only wear cotton stuff when just running around town, running errends, or commuting. cotton in winter around here sucks b@lls.
best find: $18 framers gloves found at home depot. burlier than most bike gloves, yet still a tight and durable fiit; wihtout padding, which i dislike in my bike gloves other than road riding.
lake mx-165 shoes when it's a ride that might have some hiking involved, a pair of sidi something or others when not. the lakes are great for hiking, the sidis blow.