Building your shoe collection
Black cap toe oxfords:
The first (and possibly only) pair of quality dress shoes every man must invest in is a pair of plain black capped toe oxfords. This is not negotiable. Every man must have these in his wardrobe. Even if you rarely wear dress shoes, you will have plenty of occasions to wear them throughout your life. And if you do regularly wear dress shoes, you will get plenty of use out of them as they are the most classic and timeless shoe.
Remember if you invest wisely and you look after them, they will last a lifetime. You will wear them to job interviews, to your wedding, to your children's baptisms, to your children's weddings, and eventually to your own funeral. Have some respect for yourself and those around you by buying a decent pair rather than spending 50 dollars every time you find yourself in a situation where you need them.
From there it's up to you to assess your needs based on your profession and lifestyle. Perhaps after buying your black oxfords, you decide that's all you need because you only wear dress shoes twice a year. Perhaps you wear dress shoes every day for work in which case you will build up a larger collection. Perhaps you need to wear dress shoes but also require more casual shoes in which case you will mostly invest in derbies rather than oxfords. Perhaps you look great in a certain colour, so decide to buy several styles in the same colour. Or perhaps you live in a cold climate so invest in dress boots (of which I know little).
If you do wear dress shoes regularly, as I mentioned in a previous post, two pairs is a bare minimum as you must never wear the same shoes two days in a row. They need time to breathe and dry out with shoes trees, otherwise they will degrade much more quickly. If you wear dress shoes every day, I think it's a good idea to aim for five quality pairs so you have a small but decent rotation, but this isn't strictly necessary.
I would advise not going out and buying them all at once. Build up your collection over a long period of time. For most people this is a necessity anyway, since quality shoes are not cheap, (but in the long run much better value since they will last a very long time). By doing so, you will have time to understand how shoes fit your feet, which brands work best for you, which styles you prefer. If you end up buying everything at once, you will probably regret some of your investments.
Here's the order I would proceed when building up a collection. Again it's up to your own taste and requirements.
Dark brown:
Along with black these are a staple, but slightly less formal and very versatile.
Burgundy/ox blood:
Less formal than dark brown, but they can look really sharp with the right pants.
Light brown/tan/walnut:
Again going down the heirachy of formality. This colour is less versatile, but if you pick the right style they can work great serving the double purpose of formal and smart casual.