How can I prevent mice from entering my house?
This is probably a futile exercise. Mice can squeeze through the smallest of gaps so you'd have to virtually hermetically seal your house to prevent any mouse coming in. Obviously you can block up the largest/most obvious holes and make it generally more difficult.

What you can do is make your house a less welcoming environment.

Make sure that you keep all food sealed in plastic containers etc. so that your house is not a source of food for them. They might still get in, but only for warmth.