How long do you expect to need insurance for? If you don't know, I would suggest 20 year term, since going out longer is expensive. If it is significantly cheaper, annually renewable term (ART) might be a good bargain, too.
First, look at annual rather than monthly premiums. Most insurers tag you pretty badly if you don't pay in a lump sum once a year.
Second, you want to make sure that the policy you buy has a minimum of 10 years conversion option, preferably 15 or 20. This allows you to convert your term policy to a permanent one without going through underwriting again. Chances are you will never need it, but the option is a valuable one.
Third, make sure that the fixed rate goes for all 20 years, assuming we are talking about 20 year term. Some companies only fix the rate for 10 years, then it goes up.
Fourth, stay away from "return of premium" term. Bad deal and sleazy product.
How to shop: Go price policies on insure.com to get an idea. Then hit up TIAA-CREF (website), Ameritas Direct (website), and USAA (I think you have to call them). If one of these three is competetive with what you see on insure.com, go with them in the order presented. All thre are stand-up companies with excellent ratings, a good history of treating policyholders well, and are mutuals (no stockholders).
If you have a question on a psecific company, feel free to ask, as I spent years analyzing this industry and had insider access to dozens of management teams.
