Hm I suggest you go into the forest and look for a proper place/branch beforehand. When the day comes, the last thing you want is to look around the forest and probably be all nervous if you find a good spot or not. Plus, it's pretty dark at night.
Hmm I think there are usually all kind of different trees in a forest, some with lower branches, some with higher ones. I always found a tree I can climb on in the past. But, that could change when you go further into the forest to not be found. Maybe because the trees are closer to oneanother, they tend to have their branches more up in the treetops. But that's very hypothetical now, I will go in the next days to check. Probably you just have to look a while and you will find your spot.
To be honest, I don't really care if my body is found. I just want to end it. Should I care?
I could but a note on my desk, which would be found since I live my parents at the moment. When they don't see me for a while, they will probably check my room. I want to write at least one good bye letter anyway, so in it I could also tell the people where I roughly am.
I definitly don't want to send a mail or a letter, in case I don't succeed with my plans. A letter on the table can easily be removed.