When your cue’s leather tip wears down to the thickness of a dime
it’s time to replace the tip. Six steps to do it yourself :

Step Ⅰ: Remove the Old Pool Cue Tip
Use a razor blade, sharp knife, or pliers to either cut or pull off the old
tip from the end of the cue(Be extra careful removing your old tip so
you don't gash the side of the ferrule or your fingers).

Step Ⅱ: Clean the Pool Cue Ferrule
Scrape off any remaining old glue from the ferrule using blade/
knife,and use 60 to 80 grit sandpaper to sand down and smooth the
end of the pool cue to make the surface as even as possible.

Step Ⅲ: Prepare the Pool Cue Tip
Place the new tip flat side down on a piece of 400 to 600 fine grit
sandpaper and use slight, but even pressure to sand the tip using the
sandpaper until the tip is smooth on the back side.

Step Ⅳ: Place the Pool Cue Tip on the Ferrule
Apply a few drops of glue to the top of the pool shaft. Note always use
a non porous glue and standard super glues will rot the shaft wood
and also affect the cue tip. Place the cue tip flat side down on the
shaft and make adjustments as necessary so that the tip lines up in
the center.Use the slider to hold the clamp in place. Let the glue dry
for 10 to 15 minutes.

Step Ⅴ: Cut and Sand the Cue Tip to the Ferrule
Cutting the tip to match the diameter of your ferrule.Be careful not to
sand too much on your ferrule.

Step Ⅵ: Shape the Pool Cue Tip
Use the fine grit sandpaper or a tip shaper tool to gently sand the
edges of the tip to make it smooth for billiards play. Your pool cue will
now be ready for use.