A home weather station can be a very useful tool however to get the most out of it you have to make sure that you mount it in the proper location. When professional weather stations are set up they are put in large open spaces so they will not be affected by buildings around them, this is why most of them are at airports. This is obviously not going to be an option with a home weather station so you are going to have to mount it in a way that it will give the most accurate readings possible.
In general you can mount your home weather station wherever is most convenient for you, there are however a few things to keep in mind. The biggest is that the anemometer, the instrument that measures the wind speed, and the rain gauge need to be in open areas. The reason for this should be obvious, if you have anything blocking them they are not going to get accurate measurements. Ideally you should get the anemometer above all of the buildings in your area, professional weather stations mount theirs on top of thirty foot poles for this reason.
Since you need to get the anemometer and rain gauge in a location where they are not going to be blocked most people choose to put theirs on the roof. This works great for wind and rain readings but it creates a new problem, it means that the temperature sensor will be in the direct sunlight. Even worse most roofs are dark color and as a result get very hot. This means that the temperature will read higher than it should.
If it is at all possible the best option is to put the rain gauge and anemometer of the roof and the temperature sensor under the eave so that it will be out of the direct sunlight and not be affected by the heat radiated by the roof. This should give you the best readings possible.
There are a couple of disadvantages to mounting your weather station on the roof, the biggest is that it will be inconvenient to get to when you have to do things like change batteries if you are using a station that uses them. The other issue is that if it is on the roof it will be exposed to lightning so it will need to be grounded.
If you don’t want to mount your home weather station on the roof you can normally put it in your yard if you have enough space. The only real issue here will be finding a spot where the wind will not be blocked. In this case regardless of what you do you are going to find that the wind speed will be somewhat in error.