The wooden bannister on my stairs inside my home is currently painted in a gloss polyurethane enamel oil paint (according to the can). It is thick and globby, chips off easily and is obviously covering several layers of unknown types of paint. I would like to get rid of this gloss paint and paint it over with a new color. My questions are : How do I prep it and what kind of paint would I use to repaint it? It is in a high traffic area, we have small children.

The wood is detailed, it would be impossible for me to scrape it entirely without gouging and ruining the carvings. Much of the carving is concealed with the gloss paint.

 

A physical or chemical removal of the paint...whether sanding, scraping, heat gun, paint remover...try getting of what you can by sanding, there are sanding pads and sponges that will help some with the detail...it's a fiddly job but a safe one...heat guns can damage the wood and removers are messier...in any case, once as clean and smooth as you can tolerate, prime the works with a good oil-based primer, allow to dry 24 hours, then roll on two thin coats of oil topcoat using perhaps a combination of high density foam roller and small sah brushes for the detail work...wait a day between coats...you will have a sound and solid finish that will last for years...hope that gives you something to think about...

 

you should buy a fine or medium sanding block and feather any chips where you can feel the depression. feather means to blend until you do not feel a difference in surfaces.
prime the surface with a primer that will adhere to gloss oil base.(check with your local paint store) or buy a 'deglosser' also at your local paint store.
what you are trying to do is eliminate the gloss surface and give the surface some 'tooth' to allow other paint to grab on to.
once you have primed or deglossed the surface i would recommend a 'latex gloss enamel' which is waterbase but easy to clean.
good luck