The best way really is to keep it simple. You can build a functional helicopter out of some very basic household items.

Craft sticks

Paperclips

Rubberbands

Cardstock

Masking tape

Scissors

The propeller can be picked up from an online craft store. It will be a plastic blades with a small cap that will slide over your craft stick. They are usually less than a dollar.

You will also need a pair of pliers.

Draw out a basic helicopter shape on your cardstock. About 1.5 inches tall and 7 inches long seems to be a good size. Different sizes will make it act different ways when it is time to fly. Cut it out, set it aside.

Slide your propeller onto your craft stick. It will help to put a drop of glue on first if you have any. If it fits snugly, you don't really need it. This will be your top end.

Bend your paperclip so it is open at a 90 degree angle. Set one side flat against the other end of the craft stick, and tape it on.

Tape your helicopter cutout to the craft stick. Put in on the opposite side from your paperclip.

Take your rubberband and stretch it from the hook that will be on the propeller to the paperclip. Attach it to each. You can experiment with different sizes, lengths, or even how many rubberbands you use.

Next, you just wind the propeller until the rubberband is spiraled and let it go.

See the related link for a video with tips on how to launch your helicopter.

It depends on how much damage you are willing to inflict on the Helicopter, because many techniques can damage the Helicopter and be expensive to repair. If the Helicopter is still working, you could attempt to fly it out of the tree, though this could significant damage to the blades, and the body on impact if the Heli can't stay aloft. You could try getting a ladder, if that does not reach it, maybe a few brooms taped together could get it free. You could even try to climb to tree, if it is possible.

It depends on your price range, E-Flight makes great helicopters, and they cost as much as every one else. Helimax also has a great line copters, but they're geared towards performance, and expensive performance at that. I own the "Blade SR" it's a great 6-Channel heli with a lot of potential.

http://www.bladehelis.com/Products/Default.aspx?ProdId=EFLH1500

I wouldn't go as far to say that it's THE best, but it's the best one I have. And out of a fleet of 6-Channel helis, that's saying a lot.