If you haven't already, you might have a look at the sticky posted by sailingdog:
Obviously finding the right boat is your intent, so whether you go with a private sale or broker in the end doesn't make a huge amount of difference (IMHO). There are advantages and disadvantages with each. And neither private seller nor broker has a more vested interest in your choice of a boat than you do. Both mostly just want to sell a boat. So, as with any major purchase, being an informed consumer is what is paramount. The aforementioned link gives you a good basis to go out and "kick the tires," so to speak. If you are not comfortable going out alone then, armed with a printout of the tips listed, find someone (who would be helpful) to go out and look at some boats with you. You might even practice by looking at some boats you aren't necessarily interested in just to get a feel for looking at boats and what to look for. In any case you will be able to weed out any definite no's when you do decide to look seriously. You are going to want to hire a good surveyor when you do think you have found "THE" boat, so it isn't as if you will be left to rely on your own limited experience that is primarily based on a printed off list of tips anyway. Also, this proposed exercise will be helpful when you do have a surveyor look over the boat in that you will have a better idea of what they are talking about should they find any issues that need to be addressed.
Best of luck in your search.