Prior to getting my ears pierced, a couple of years after coming out and starting transitioning, I wore clip-ons.
Unlike Caroline, though, I didn't have issues with the clip-ons being uncomfortable to wear for extended periods. In the early 1990s, when I started buying jewellery, I learned of the clip with screw earring mounts. Those mounts have a thumbscrew pad at the tip of the clip on the back, and the front stud point was usually bare. Some had a mounted diamante on that front point. You'd clip them in place, with the thumbscrew completely backed off, then carefully tighten the thumbscrew till it was firmly holding, but not uncomfortable. They worked very well.
Using tweezers and needle-nose pliers, I could fit pieces of jewellery ornamentation from other jewellery to hang from the mounting ring on the lower front of them. That meant I could go to the el-cheapo shops, buy the good looking earrings with the uncomfortable and not adjustable clip-on mounts, and re-mount the jewellery ornamentation from them, on the more comfortable clip with screw.