They've given you some great advice:
1. No matter what developers sales people tell you, 99% of the time you get the same benefits when you purchase a timeshare resale as you do when you purchase from them and you can get it at 20-30% of the developers price.
2. TUG is a great website filled with lots of information. If you are internet savy (and since you have found this site I am sure you are), there is also tons of information available on timeshares in general or even specific brand name timeshares.
3. Be patient and do your research. While "great" deals do happen on occasion, if a deal doesn't seem right, walk away, because there will almost always be another one.
4. If you buy where you would like to go most of the time, you are then not at the mercy of the trade companies and their fees and rules.
5. My final piece of advice is to also look at the trade companies and which resorts they offer before committing to buying your timeshare. The two major compaines are Interval International and RCI. If you would like to have the chance to trade into one of the DVC resorts, you would want to make sure your buy a good quality resort that trades through Interval. Trading into a DVC resort is hard but it can happen. The chance of trading into DVC is slim, but if your resort only trades through RCI, then there is no chance of this at all.
Just my two cents.