My daughter puts small post it notes on the back corners then uses command strips - attached to the post it notes and not the poster. Works like a charm!

I always buy multiples so I have extras lol. I’m full of no help to your question, but if you ever want to keep them but don’t want them up on walls I got a large art portfolio and store them in that

Adhesive Stick dots Two-Sided Sided Mounting Putty Stick Tack for Wall Hanging Crafts Balloons Festival Party Decorations,Clean Removable(100) https://a.co/d/7opLRS1. These are the best !

I just use wall safe tape and make a little circle with the sticky on the outside and put on the four corners on the back of the poster lol I don’t like putting holes in my wall and it’s easier to switch to different posters

I use deco tape or some kind of paper tape for posters and postcards, I display almost everything and I don't mind ruining them because I don't want them to just collect dust

I use pushpins that are also clips - not a hole in sight

I buy frames at second hand shops for the posters and postcards. Suga and RM are in gilt gold frames on my wall!

I don't have my own space where I can display them, sadly. So I have clearbooks. I have this really big clearbook that is the size of an SM Ent poster. One option is to get frames, then switch out the posters/postcards every so often. I also try not to directly put adhesive on them. I usually have a sleeve or so.

I have a coffee table that has a glass top on it so I've put some posters and cards under the glass. It looks really cool. Also photo frames and I also made a board with elastic strips so that I can put multiple PCs or larger pics in it. The elastic holds them in place and I put coloured thumb tacks in between cards to also help keep them in place as well. You can make an awesome collage with it or put them however you feel like.

Mine are still in tubes but I plan to frame them