For most small businesses, if you position your services as IT consulting, advisory, and support, you can easily transition between disciplines.Networking, software, true consulting (planning, strategy, vendor selection, etc.).
As a general rule, avoid being the “computer guy” - which ends up being the “break/fix/support tech guy” and relegates you to that work only.
I have an article at informit.com on starting consulting part-time and moving into full time consulting work.
http://www.informit.com/articles/article.aspx?p=2141277
Also, I have, “12 Weeks to Profitable Consulting,” one of the chapters of my book available as a free download. And no, you do NOT have to give me an email address or anything else to get it… at least, not yet.
http://www.itcareertoolkit.com/12weeksconsulting/
Regarding Rates:
While I understand the concern about pricing yourself out of the market, I strongly recommend you establish a rate of at least $100/hr - and avoid companies that balk at that. Chasing lowest cost provider work is wasted time. Make yourself a boutique and trusted advisory to the best clients. As soon as a client questions an invoice or late pays an invoice more than 1 time, find a new client so you can prepare to drop the slow pay client.
Also, setting a reasonable (for you) rate is important because, if you DO NOT allocate time for administrative tasks, sales & marketing, and other downtime, you will not be able to stay in business. The mistake many consultants make is believing they will be billing 40 hours per week for 50 hours a year.
Determine what you need/want to earn in a year and calculate how to get there if you billed 25-30 hours per week and worked only 9-10 months consistently. You can end up with more, for sure, but using this calculation you can account for your own sick time, vacation, administrative time, sales & marketing, etc.