I have become a fan of the sun protective long sleeve shirts and of long sleeves in general. I try to wear them all the time now.
I don't understand the comments that a t-shirt is only SPF 7. I am very pale skinned and I have a lot of experience with sun and sunscreens. I have never so much as gotten tanned under shirts, not even a tiny bit (there would be a bra line). But I can burn with SPF 15 sunscreen.
If you are allergic to a thing, it is best not to put that thing in your mouth, particularly if the thing is cats. - Lemony Snicket
Blond hair, blue eyed, fair skinned girl here. For those who really hate to wear sunscreen because of the heavy greasy feel, definitely try the spray-on sunscreens. They are SO much lighter and don't have a greasy feel to them. I don't even notice I'm wearing sunscreen. I especially like the Banana Boat brand - bought the Coppertone version last week and it actually made the color bleed around the neckline of my t-shirt where I sprayed it on the back of my neck! The Banana Boat never did that. Just make sure to apply evenly - easier said than done if you're in out in the wind! I much prefer this to the lotion when working outside or at the barn where you can get sweaty and dirty.
"Farming looks mighty easy when your plow is a pencil, and you're a thousand miles from the corn field." --Dwight D Eisenhower
Hats, long sleeves, sunglasses, zinc oxide sunblock -- all good. But don't forget time of day.
I am a real vampire and hate the sun, so I make a point of going to the horses in the morning before 9:00 am or in the afternoon after 4:00 (usually even a little later.) I had read some info about Australia's efforts to reduce skin cancer by changing recess times at school to prevent sun exposure on delicate skin of young children during the dangerous times between 10am to 2pm, which was prompted because Australia, with its large number of light-skinned people and sunny weather, has the highest rates of skin cancer in the world.
I think it is also good to consider shade structures in the design of your barn and facilities. I will not be able to afford a covered arena, but I will have a covered round pen, barn, grooming area, and plenty of shade trees.