Sun is a good thing to generally avoid. I try and stay out of it as much as possible, always have. While all of my more sun-loving friends are developing crow's feet and bad skin, I remain wrinkle-free at 37. :-) I prefer pale porcelain skin to tans anyway.
These days, I do spend much more time outdoors because of work, and it's entirely too hot to wear long sleeves. But, I usually wear hats, long pants, and at least 30+ sunblock on my arms whenever I am outside, this has minimized the farmer tan look.
If you are working outside, you can also get sun sleeves, sun blocking elastic material that you just slip over your arms. You still get the air circulation of short sleeve shirts that way.
Also, turn on the air conditioning in your car and roll the windows up in the summer. It may use more gasoline that way, but you'll be more comfortable, and the glass blocks a lot of UV. On the freeway the fuel mileage loss will not be as noticeable since your windows are up, aerodynamics are usually better.