I only put up authentic movie-posters, which are pretty big (27" x 40"), and I find that any kind of tape will damage both the posters themselves and the paint on the wall as well. Stick-tak stuff always leaves an oily residue on the posters, and it bleeds through from the back to the front where you can see it. Thumb tacks are okay but again you can see them. So my solution, albeit an expensive one, is to Plak all my posters at the local Costco. It costs about $30 CDN for each poster, but they look professional and really awesome when up on the wall, and you only need one good-size nail which you'll never see because the poster covers it.