The most important thing you should learn first is how to change the parameters of each effect , and how to save your setting... I think that there was a small (couple of pages) pamphlet that comes with Boss products called Turbo or Quick Start , read it thoroughly.
From my experience with my GT-3 , I say experiment with the factory set patches first , then do the fine tweaking till you find your optimum tone and save.
The better (harder) way is to make up a patch from nothing , but it's gonna be hard & time consuming since you've got lots of options & combinations to try first.
I've found a lot of GT-3 & GT-5 patches online , and I can tell you that you're not going to find what you're looking for , because of the different amps and so ... I recomend that you waste time with your GT-6 and learn how to get the most of it , instead of wasting your time searching for patches (that you'll eventually don't like) online.