You should do clues 4, 10 and 12 first - all of which are easy. The key to the whole puzzle is then clue number 7. You have two options for number 7 and clue 5 tells you which of the two possibilities it is...the house on the far right has to be yellow! The other clues fit in easy from there.
1. The German lives next to the white house.
2. The man in the yellow house drinks milk.
3. The man with a mouse lives next to the man with a cat.
4. The Englishman lives in the first house on the left.
5. The man in the white house drinks orange juice.
6. The Italian lives in a blue house.
7. The yellow house is on the right of the white house.
8. The Frenchman has a dog.
9. The man in the red house has a cat.
10. The man in the middle house drinks tea.
11. The Spanish man drinks cola.
12. The Englishman lives next to the green house.
13. The man with a horse drinks tea.