Can someone help me? What do I have to consider in building a house?

Don't forget permits!

We just did this 6 years ago and with a bit of planning you will be very happy. My suggestion is to put most of your windows on the South side of your house if you can. Passive solar heating can help in a cold climate, if you have any kind of winter. With the right builder the permits needed will be gotten and thing should go smoothly. Depending on your age, you might consider a ranch style so there will be no stairs as you age. Also if you like to be outdoors at all get a nice porch put on. You can enclose it later if you desire, however a porch is a good place to gather in warmer weather. Think about how you are living now and try to incorporate those ideas into the new house.

I don't know what the laws are like where you are, but in Europe, you tend to need planning permission before you can build. So the first thing you should do is check out your local law, see if you need planning permission and what the requirements are. Some places also prescribe what type of home you should build so that it doesn't spoil the locality too much by looking out of place.

you need to consider a lot man.. but congrates for the start up. you need to check what kinda house you want to build i mean architecture, time frame in which you want to complete, arrangement of water and electricity supply and other necessary formalities from your local government may be required.