This is what worked for me playing banjo uke in an old time string band:
A D F# B
(D (dog) is the lowest, A (my) is a full step (two frets) higher than B (fleas)). It's similar to the high strings on the 7th fret of a guitar, except the A is an octave higher than the guitar's string.
Metal strings for your banjo uke:
I use Jim Dunlop nylon .73 mm grey picks. If you stick with the same pick, you'll break fewer strings and get control of your sound.
Wrap your middle and index finger first knuckle with medical tape before you start playing. You are working with an egg slicer.
Get an archery arm guard to protect the inside of your right forearm. Even if you have an armrest you'll get a terrible infected abrasion on your arm if you go to a festival and play all night without one.