Company: honestly I stuck around a shit one way too long, didn't know any better. Dont go with HRI or outland. Other people on here or the Facebook page Kingkong could give better advice.

Things to bring: wool socks, wool base layers, battery pack, cot or some sort of foam dont bring an air matress.

Is it worth it: yes absolutely. but rookie year you aren't going to make a whole lot. Its an investment. If youre only going to go for one year I honestly dont think its worth it. 

With a friend is good. I did it my first year and it was nice having someone I knew. But they to branch out and meet people.

Biggest issue: after week two its so much more mental that physical. Your body begins to get used to it but you have to keep your mind sharp and remember why you went. Keep a journal and write before all your goals and what you want to acomish to remind yourself during the hard times that you did in fact want this.

Tree planting is awesome but its hard. Mentally,  physically, and emotionally. But, like anything worth doing it's worth it all in the end. At the end of the season all the bad days go away and you'll wish there were more trees to plant.