It makes a lot of sense for small to medium enterprises to outsource and use IT consulting companies for any large IT projects that they may have. You get experienced workers without the problem of having to keep them occupied after the project is finished. But there are a few things that you should do to protect yourself from all of the fly by nights out there.
Any IT consulting contract that you sign should be read by your lawyer. This is not to say that all IT consulting firms are out to get you, but you may think that you are signing up for one type of service but are actually getting another because you do not understand all the jargon. Your lawyer will also be able to show you all the potential areas where you could incur extra fees.
IT consulting companies often charge by the hour, whether it is through an SLA or ad hoc work. Make sure that you get a full record of all the work that they have done so that you know what you are actually paying for.
Second opinions count
It does not hurt to get second opinions on what is being done by an IT consulting company. Sometimes there is a quicker way to do things that your contractor has not thought of. Sometimes a new viewpoint can shed light on a problem that has been taking far too long to fix. Do be gentle about it though and try not to point fingers or name names as this can lead to a bad working relationship. Once you trust your IT consulting company, then you can leave them to do the job. But a second opinion near the start of the project can definitely give you some peace of mind.
Any IT consulting company that is worth their salt and is honest should have no trouble with you doing these things. They would understand that you need to look out for your own interests and make sure that they are doing their job properly. If they get up tight and offended, they might just be sneaking something by you.