I worked in a frame shop for several years and there are a few different ways to go about it, but some general guidelines...
You don't want prints to be touching the glass. You should either mat them, or make sure to request that the framer put in spacers. Spacers are just little pieces of plastic that sit between the glass and the picture. They are completely invisible in the finished product and you won't even know they're there.
If you need to use backing on top of the board behind the prints or want to use mats, make sure you only use acid-free or archival quality materials. Things like regular paper mats will give the print's edges a yellowish tint and make the paper more brittle. Any frame shop you go to should sell acid-free materials, even the cheaper chain ones like Michael's and Hobby Lobby.
UV resistant glass is a good option. Even if it's not in direct sunlight, if you really want to protect the prints (and have the option of moving them to other places in the future) it does help preserve the ink.
You should also steer clear of buying any premade frames. They're typically made out of very cheap materials, most of which an actual frame shop would never even use.