I have to chime in on this.
A rate increase can be justified so long and you don't get too agressive. The costs of things are upright now with fule in the U.S. on the rise so that alone could make it necessary for someone to increase rates. We use a flat rate model and are trying to keep rates as low as possible while still maintaining realistic profit margin.
In the case of flat rate services you may a $5.00, $10, $15, or $20 increase depending on the services. In most cases this increase will not negatively impact you potential clients.
I think that rather than just blindly increasing rates a full examination of your business would be very wise. Take some time to really look at overall expenses, income, etc and determine what you need to charge to earn what you need to year. I have been spending the last week doing a numbers dive and examining all the service records for 2010 and found some areas that we need to improve. Some of these involve pricing, others involve processes, and still others involve improving communications with clients so they understand the value of services better.
All of these things can impact profitability which in the end is what we are actually talking about when considering a rate increase.
So I would say what can you do overall to increase profitability in 2011 by 30% and what can you do to increase the number of work orders by 10%, 15%, 20% etc. If you can increase profit AND increase your work orders then you will have a very successful year.