Drill holes in the bottle of the bucket using a series of 3 drill bits, going from smallest to largest.
Using the bottom of the bucket as your size guide, cut the screen to fit inside your bucket.
Place the screen inside your bucket. This will reduce the amount of soil that comes through the holes and eliminate the need for a saucer. You can a few drops of gorilla glue here to keep the screen from moving around, but that is totally optional.
Add a thin layer of gravel to weigh down the screen and reduce loss of soil.
Fill with dirt to proper height, using your plant as your guide.