When I do seminars I tell attendees that I decorate trees from the top down and the inside out. Think about that for a second.
Put the star, bow, angel, whatever you use to top the tree on first because you can get yourself into the tree to attach it securely. If you wait until the rest of the tree is decorated, you run the risk of dislodging decorations that you have painstakingly attached to the tree.
Start at the top and put the topper on.
Test your light strings and put them on the tree next, beginning at the top and run the lights from the inside of the tree out to the ends of the branches and back into the interior of the tree. I apply the lights on the tree in sections, going vertically. I find this easier to do than to wind them around and around the tree. It also makes undecorating easier. As to how many lights to use? My rule of thumb is a minimum of 100 lights for every foot of tree height. However, if you double or even triple that, you get much more light effect. It is up to you. I usually use a combination of strings that are always on with a few strings that flash or twinkle.
I put larger, light reflective ornaments in the interior of the tree. It gives your tree depth. Don’t just decorate the tips of the branches.
I add garlands next. Again, I resist the urge to wind them round and round the tree. As with the lights, I take them into the interior of the tree and bring them out again.
I add the ornaments next. First the inexpensive ones and finally the expensive glass ornaments. I use inexpensive wire hangers to secure them to the branches, bending both ends so there is no danger of the ornament falling off. One customer of mine uses ribbon and ties every ornament onto the branch. I am sure this results in a beautiful effect.
Finally, I add the picks and if I am going to use it, tinsel or snow. I add these items last because I rarely attach them to the tree. They are normally just laid on the branches.
These are just my methods. I hate to call them rules. Each of us should decorate to please ourselves. You will have more fun if you adopt that attitude.
If you have suggestions that you think work better, please comment.