Proper pruning is essential to ensure a healthy, long-living tree. Simple tree pruning can certainly be done by homeowners, but there are a few guidelines you should follow:
1. Do your research first - Check out a book on tree pruning from the library, do some internet searches, or take a look at the links on the bottom of this post. If you're unfamiliar with tree pruning, you'll likely do more harm than good.
2. Don't be afraid to consult a professional - It's important that you don't take on more than you can handle. If you're unsure about what you're doing, you should definitely consult a pro as opposed to doing something unsafe, damaging to the tree, or ending up with a result that you're unhappy with. Even if you want to do the work yourself, a professional arborist can give you free or cheap advice.
3. Be safe! - Make sure that you constantly have safety in mind. Never attempt to trim a tree that has branches in power lines. Again, don't try to tackle too big of a project on your own.
4. Be observant - Keep an eye on any dead or disease-ridden branches or leaves. Invasive insects can also be a problem. If something looks out of the ordinary, consult a professional arborist.
5. Don't trim inappropriately - Tree topping (see picture below) is one of the more common mistakes in tree pruning. As you can see, topping results in an extremely ugly tree that does more harm than good. A topped tree will become hazardous due to weak branches, and it becomes more susceptible to storm and insect / disease damage. Tree removal and replacement is preferred to topping.
Resources:
USDA Forest Service guide on pruningNational Arbor Day Foundation pruning animationSpokane County Conservation District - Free advice on tree careIf you have a tree with branches in the power lines within the City of Cheney, call the Light Department at 498-9294.