Set up the bucket in a good place for resonance. Choose ground or floor areas that are hard and smooth; tile, cobblestone and pavement will make for a much better sound than carpet or grass.
Place one bucket rim-side up (if you have multiple buckets). This will allow you to utilize both the sounds created by the drum when it's placed upside down as well as the dryer, sharper sounds of a rim strike on the top of the bucket.
Master a basic roll technique. Hold your drum sticks correctly; there are different, correct ways of holding snare sticks, but street drummers often prefer a "match stick" grip; hold each stick in your hand between your thumb and the middle knuckle of your forefinger. This grip is secure, but will allow you to let the stick flop and rotate enough to bounce when you strike a surface with it, creating a roll.
Strike plastic buckets hard. These objects are not created for resonance in the same way real drums are, so they require a bit more force to speak loudly enough for an audience to hear.
Experiment to find as many different timbres as you can. Try different ways of striking the bucket in different places, such as hitting with the tips or back ends of your sticks, hitting the center of the bottom vs. hitting the edges, and striking the sides of the bucket for a booming drum sound. Typically, street drummers will also tap their sticks together and drum on the pavement around them to add some dry, clicking sounds to the performance.
Create music with a wide variety of sounds and rhythms. Use your vocabulary of sounds and rhythms to create musical performances with a lot of variation in order to keep your listeners interested. Remember that like any instrument, a plastic bucket is not great on its own; the real value of the performance comes from the creativity and preparation of the artist.