Generally speaking it is best to avoid any kind of perfume (your soap or your sun lotion can contain some, and obviously deodorants or God forbid perfumes, sorry if I treat you like a sissy ).

Generally speaking it is best to avoid any non-mimetic colour because in the wild you don't want to disturb any form of life and you want to see wildlife. Colours like red can have specific meaning especially for birds and normally birds are guaranteed to become "nervous" when something red approaches, so when wearing brilliant colours you are going to see much less birds than when wearing mimetic clothes, and you might even disturb/prejudice some nesting more easily.

Bees fly to their pastures in straight-line routes. When an animal (including a photographer) stands in one of those straight lines they begin bothering him so that he moves away from the route. If some bees disturb you (they seem to be interested in interacting with you, not necessarily in a friendly way) sometimes it's enough to move a few meters to have them cease the disturbance, or so I'm told. I actually think I experienced to truth of this many years ago.

Generally speaking it is best to avoid short pants especially when laying down in the grass in regions with domestic animals such as sheeps, cows, horses, you get the farm. Those meadows are infested with lice which do not limit themselves to sheep but do maintain a prejudice-free opinion regarding acceptable food.