The best thing to do is to play around with them and see what works best for your phone. Just make sure that the "Start of boot" box is NOT checked.
I have mine set at 528/787 and haven't seen any problems with it thus far. As far as profiles, I just have my failsafe set at 40 degrees C. That temp is what I've seen most people set theirs at.
To optimize performance, it's best to have the min/max as close together as possible. However, this will likely drain your battery with respect to your settings.