Some people say it's best to try regular wax from a candle first, and leave beeswax as the second option, in case that doesn't work.
The main difference is that beeswax is stickier and hence more likely to pick up dirt.
I've never had a problem with a loose fitting fiberglass ferrule that beeswax couldn't solve, including for a 5-pc. 7' spinning rod that was giving me problems.
The bigger problem is incremental wear on a spigot-type glass or graphite ferrule, to the point where the tip starts closing the little gap between sections that those rods are designed to have. That has a way of leading to splits in the female end of the connection.
The best way to deal with that is to catch it before any evidence of splitting shows up.
To fix a worn ferrule spigot:
First, clean the ferrule with a bit of soap and water and let it dry off.
Next, mix up a little bit of epoxy, paint a thin layer to cover the spigot joint completely. "5 minute" set-up epoxy seems to work as well as the more long-drying stuff.
Give it a minute to get a little tacky- then wipe it off of the spigot with a paper towel or a wiping cloth.
(I like to use those little soap-saturated cloths that you can buy in packs at the dollar store- rinse the soap out of one and let it dry, and they're ideal for little finishing jobs. They also work well to get excess Mucilin or floatant off of fly line.)
Then let it dry completely. Completely. (Follow the directions.)
That's usually all it takes.
But if you find you've left a little too much epoxy on the ferrule and the fit is too tight, it's pretty easy to make a little rope loop out of 0000 steel wool (sold at auto parts stores everywhere) and buff the excess off by twisting the loop around the spigot to sand it off. Light pressure, no more than one full turn at a time, the length of the spigot.
If you find you've over-sanded, repeat the process until you get it right.
There's almost no way to screw this repair up as long as you clean the ferrule before doing it, and don't join up the rod until the epoxy layer is completely dry.
But if you find that the female ferrule joint on a section has already begun to crack and split at the end, the section will need to be sanded or trimmed to above the splits, and possibly reinforced. Most people prefer an experienced repair person to do that.