Oh, the things they did to old homes in the 50s and 60s. Among the atrocities was dropping the ceiling and putting 12" square tile up. So here we are in the new millennium taking down all the dropped ceilings and putting up drywall. If that isn't in the budget, yet you can't bear looking at it any longer, I have some ideas for you. A technique I have used in the past is to stencil on the tiles using spackling paste. It gives the raised design that looks like a tin ceiling. Caution: This project is very labor intensive. I did a small room and worked directly on the tile over my head. My shoulders and neck suffered for it but the results were great. Another approach that I'm experimenting with is to stencil using the same technique on foam core board, then use construction adhesive to attach the tiles you just created right over the old ones. This might be a better approach for a large ceiling to save your neck. Once the spackling paste dries, you can paint. White works great, or use a paint Rust-Oleum makes called Hammered Silver for an authentic tin ceiling look.