You should also learn how to work around cattle by helping someone else with dairy cattle. Otherwise, you can get kicked, stepped on, smooshed, gored, bitten, mutilated, and even killed because you don't know the simple basics. Having a few weeks of experience with someone else's cattle will net you a shit load of knowledge in a short amount of time. You'll then be able to decide if dairy cattle are what you would like to do. You may find that you would rather deal with milk goats. There are also some dangers working with goats, but usually only billy goats.
Regardless of goats or cows, you need to find a vet who is willing to come to the farm for visits. You'll need to get stud service for your livestock; which is the best option for breeding larger animals. You should find someone in the area with a cattle trailer you can hire if ever needed. Goats can be hauled in a standard pickup truck with a proper goat-proof cage. You need all the infrastructure to deal with either of them. Like fencing, multiple paddocks, stables(birthing, quarantine, whatever), corral(s), loading/unloading shoots, milking station, vet station, feed troughs/bale feeder, and anything else I'm not remembering. Most of that stuff can be built with rough lumber and isn't expensive if you are DIY enabled.
You'll also need to decide what you'll do with the offspring of your livestock. The easiest thing will to sell them at market when they are young. You'll get a quick return of money and not have to deal with extra livestock and their costs. Though, you may want to have a few spares, in case of emergency. While you can do your own butchering, it is advised to send the livestock to a reputable butcher. It is so much easier for cattle. For goats it is like working up a deer and not too bad by yourself.
Look into local feed prices for grain, hay, and silage. Consider your land area for pasture, learn how to maintain a proper pasture, if you have the room. Rotate pastures as needed.