Are you comfortable using an electrical meter? If not, then your best bet would be to call up friends and find out who they have used (and whether they are happy with them or not) and get with that company.
If you know how to handle a meter, then how about some specifics, such as make and model of furnace, does it "try" to start up (makes noise, but nothing happens), or does it not do anything (did you check the breaker?).