It is pretty easy to do a google/yahoo/bing search and find tips on doing focus groups. You can learn reasons "why" you should do focus groups and even how to conduct them.
But a word of caution. I was just looking at the guidelines for writing an article for a top ranked site and came across some focus group tips.
I disagreed pretty strongly with nearly all of the tips because they were either a waste of money/time or because focus groups was the wrong market research method to use for the information sought. The person giving the tips was an amateur and was suggesting that you just go out and do your own focus groups. Wow.
Here's an example. One of the tips was to have respondents take some time and read something, write it down and then give their feed back on it. This is a real value suck to a client. Are your focus groups exciting? Hey, let's spend a bunch of money to watch people read and write...and watch paint dry too.
A better approach is to have people do a pre-group questionnaire or give them a homework assignment before they arrive for the groups. It's a great idea to have people bring in homework or even a daily journal of what they typically do with your client's product.
The consultant or "tip writer" who was recommending that folks write down their ideas was suggesting this was a way to keep people from influencing their neighbors answers. And at times, you might do this to prevent bandwaggoning and group think, but it is important for it not to be a long task or general task because what you may end up doing is creating "a simulation of something that would never happen in the real world."
It's kind of like when a "newbie" person asks price questions in a focus group. Could be a career ender for you or your client's company to do pricing studies in a focus group with no quantitative research. Look at this dumb qualitative question: Is the price of popcorn too expensive at the movies? Yes. But that is the wrong question. The correct question is "Do you typically buy popcorn at the movies? The answer is also "yes."
So, the exercises you do in a focus group need to be well thought out. Don't just let people read and write - if for no other reason than the cost per minute of doing so in a focus group. Also watch out for those "free tips" and people who think they can run a focus group. It may be worth less than the popcorn you buy at that movies. In fact, the information you gather may clog your company like the "movie popcorn butter" may clog your arteries.