I used to use Kiwi wax polish on leather boots and shoes. Like the other posters mentioned, it can dry out and crack the leather, but the environment I was working in ate the soles long before that could happen (non-skid coated steel on a ship).

These days, for dress shoes I use Meltonian cream polish. It leaves a nice, lasting shine. I do a really thorough job like once a month and the rest of the time I just brush out scuffs. For boots I use Meltonian cleaner and conditioner, which helps with water resistance, gives a nice shine, but doesn’t cake up. Don’t get hung up on brands, but that’s what works for me.

As far as technique goes, I apply with an old t-shirt I’ve recycled into a rag. After it dries, I buff off the excess with a brush (I think mine is horse hair, sorry horses. At least I’ve had the same one for like fifteen years now), then polish to a shine with a different t-shirt rag.