I use the primocon primer/prop paint from Interlux. It is not perfect but it certainly improves things compared to completely bare prop. (It is also easier to clean off barnacles from paint and primer than it is from the bare metal).
Make sure to use primer first as specified on the packaging. I tried a shortcut a few years by just spraying paint alone and it tends to not hold as well (d-oh).
I've had good experience with Petits Zinc Prop and Shaft Spray. A spray paint zinc coat that is easily applied. I was so happy with a single coat last year that this Spring I put on 3 coats. Hey if a little is good, I'm hoping more is better. Anyhow, last season I experienced little barnicle growth and what was there was easily removed. Not inexpensive but less than $30 for a spray can.
Several people have told me they use "penatine", it's a zinc-based diaper rash ointment for infants - really!!.... quite sticky and seems to stay on the prop, and does the job.... probably costs less too...
Grease I had an Autoprop on my last boat and at haul out I'd grease the prop bearings then appy a thin layer all over the prop. While it does wash off the prop seemed to have fewer barnacles on it then prior to doing so. I've heard of people using lanolin the same way. Actually supposed to be the primary ingredient in Prop Speed, just a lot cheaper.