For your average single pitch sport climb the most complicated ropework involved is arguably when it's necessary to thread the anchor in order to lower-off. And if you've only climbed on indoor walls it's something that'll probably be new to you.
Since threading an anchor can involve untying and retying into your harness, it is important to concentrate and have clear communication with your belayer, to avoid any mistakes that could have very serious consequences. Some climbing walls have an area with lower-off stations typical of what you'd find at the crag, set-up just a few feet above the ground, to safely practice the technique.
If you're used to lead climbing indoors, then it's normally a simple matter of clipping the lower-off biner(s), attached to two independent anchor points, checking with your belayer and being lowered down. Occasionally this may be the case at the top of sport route outside but you are more likely to find that the anchors vary greatly both in terms of type and quality.
Commonly on crags you'll find two bolts linked by a chain with a central ring for lowering-off or two bolts each with a maillon and ring attached.
In the above video Ben Bransby outlines two methods for lowering-off a sport climb. One where it is possible to thread the anchor with a bight of rope and another where the end of the rope has to be used because there isn't enough room for a bight.
In the second method, where the two glue-in staple bolts don't have a maillon and lower-off ring attached, it's important that you don't add to the wear on the anchors by top-roping off them. Use screwgates and quickdraws/slings for that. If you find a lower-off like this then perhaps ask your local bolt fund for maillons and rings and equip the anchors with them next time you're at the crag, so any wear is on the rings rather than the bolts; which are far more difficult to replace.
A couple of other points to keep in mind are: always inspect the quality of the anchors and the rock they're in before committing to them, never lower-off a rope threaded through a bolt hanger as the square edges may damage or cut your rope and if you find any rope or slings at the anchor, never thread your rope directly through them.