I started out as a teenager doing tips in the local pool hall. That was 60 years ago but you can still get acceptable results with $50 worth of tools. Buy a tip top sander. Get a 6"x 6" x 1" block of hard wood. Get a razor knife, some thick elastic bands, instant glue gel, LePro or Triangle tips and some 320, 400, and 800 sandpaper.
1. If there is a tip on the cue cut it off with the razor knife.
2. Sand the ferrule flat with the tip top sander.
3. Sand the back of the tip flat. Put a thin layer of glue on the tip.
4. Place the tip on the shaft and hold it there with the elastic band.
5. After the glue has completely dried (10 min) turn the shaft upside down with the tip on the block of wood. Using the ferrule as a guide start trimming the tip even with the ferrule using the razor knife.. Continue trimming until the tip is round and close to the final shape you want.
6. Use the sandpaper to smooth the tip to the ferrule by going from coarse to fine
7. Wet the edge of the tip and then burnish it with a piece of leather or any other suitable burnishing material.
Once you have done this a few times you will be surprised at how good the tip will look. May not be professional but most people won't notice the difference.