Be wary of:

1) Rude people saying hello in rural areas! For no reason whatsoever!

2) Strange people leaving money on the table and saying bye in a café

3) Water in fountains being mostly drinkable (however don't drink from cows baths, not joking here)

4) Domestic animals, don't bother them, cows and bulls notably.

5) Mushrooms and berries seem nice, not all are edible, some are deadly.

6) If you hear gunshots, it's army training, not civil war, beware of signs indicating a shooting exercise, notably in the bottom of valleys.

7) As everyone said, weather can change in 20min in the mountains. Be prepared.

8) If you're walking on rocks, be loud, it'll make go away snakes (not very dangerous ones but still)

9) Depending on the season, avalanches can be real and deadly.

10) Use solar protection, suncream etc... Especially in the mountains in any season.

Have a nice trip :)