When you handpicked and bought a banjo or even made yourself one, you eventually have to tune it. Some say that banjo can never be tuned, but here are some methods.
First it is smart to do a check on the banjo. With tightened strings check the place where the neck merges with the rim of the banjo. There should be no errors, looseness or twisting of the neck. The joint should be rigid. Should the banjo stay in tune after you manage to tune it depends a lot on this joint. If the joint is flexible the banjo will never stay in tune.
It is important to buy quality pegs and strings, for they will also contribute to the effectiveness of the tuning. If testing a banjo, ask the owner, if you may put them on the banjo, as this is always a good excuse to thoroughly examine the banjo.