This is my first time wearing a flat back earring, and it was really, really difficult to screw together since I'm wearing nails, but even my mom had a hard time screwing them together, and she has short nails. If you're worried the back post won't fit into your ear, don't worry, because I got pierced with a gun and have only ever worn thinner posts (20 gauge), and it still went in. You just probably need patience, vaseline, and another person to help put it in. Tini Lux also has instructions on their website for wearing flat backs, so definitely look into that if you want to start. My only complaint with this earring (no star deductions though) is that the length of the screw, because as I've mentioned, the post is too short and the piece doesn't feel narrow enough for it to easily attach to the back post. It took me about 100 times to get it to attach before it fell because the post didn't have much to "grab" onto, so I could screw it together. I think if the screw were a little longer with a narrower point, it might be easier to get them in. There's nothing wrong with it when you do get it in, just make sure you screw them in properly. But for the record, these are much smaller than a regular stud.
Since I haven't worn earrings in a long time in my second lobe due to having metal allergies, I did have slight itching/irritation, and I also hit the piercing, so it was kinda hot, but it went away in the next few days as my ears got more used to having jewelry in them so if you notice that just give it a few days and use a saline spray and you should be fine. This is the first time I've been able to wear earrings without any irritation (I also got the castor studs), and even though the post was thicker than usual, my irritation has fully subsided, and I've been wearing these for about a week now with no problem.