This item can have a dramatic effect on your tone. For bluegrass, a plastic head by Reno or the 5 STAR Stew-Mac is recommended. The white, frosted style is preferred. The frosting does help keep the bridge from sliding out of place. Clear or smooth white heads tend to give a slightly brighter tone, but head tension has more to do with that than choice of plastic. There are some plastic heads that are a bit thicker and that will bring about a darker tone. There is also a Fiberskin head, still synthetic but made to look and feel like actual skin head. Skin does have a nice mellow tone but is not practical for the everyday player. They need to be adjusted constantly for optimum tone. Most bluegrass players prefer the Weatherking white frosted head. For flathead banjos, you’ll need a medium crown; archtops need a low crown.
There seems to be a critical tension zone to get the best sound out of the banjo. Tuning the head somewhere between G and A on flatheads or A and B on archtops, will give you a good place to start. With strings dampened, I’ll tap or lightly scratch the head and listen for a tone. If the head is way too loose, you may not get a tone at all. Then, I’ll fret the 4th string at the 5th fret to see if I’m close to G. Some banjos may need to go to G# or A if a brighter tone is desired. Somewhere in this range, you will find the best tone for you. It does not have to be tuned perfectly to a given note. Some basic guidelines: below G will be very mellow, bordering on dull, less-focused tone; above A will be much brighter but too tight and you’ll lose a lot of low end. The tone could get very harsh. You may need to check this a couple of times a year, depending on the environment to which your banjo has been exposed. There is no rule about how often to change a head. Some folks change it every year, other every 10 years. If you feel like you’ve lost some tonal quality and have tried other options, it might be a good idea to change it.