Strings are incredibly important. Especially in with a banjo. Since the banjos strings are thinner, they collect gunk and rust sooner. That being said, banjo strings are also fairly cheap. I would advise buying them in bulk (3+) because you will always want new strings. Replacing them is kind of a hassle at first, but necessary if you want your banjo sounding the best (which you do; one never knows when someone will want to hear you play). So, in order to set a good example, I will change my strings now.
Reminder: The bridge is free floating and will move if all the pressure is taken off. (See anatomy: Bridges)
Step 1: Loosen the string. This way you don’t have all this high tension hitting you in the arm.
Step 2: Cut the string. Use a wire cutters for this, or something similar. Remove the string and throw it away. I knot the strings so they are easier to grab.
Step 3: Start at the tailpiece. Loop the string end around the corresponding tailpiece part and fit the string into the tuner.
Step 4: Wrap the string around the tuner a couple of times and then loop the string again and tuck it inbetween loops and pull taught.
Step 5. Tune up again.
Shazaam! There you go.