Here's my advice.
• If you haven't already, as you didn't totally specify, change your graphics level to custom and then change everything to low/unchecked. This caused me to crash way less often and significantly improved my frame rate.
• Priority setting isn't really necessary and there are many people who would argue it doesn't help at all.
• Crashing because of loading areas or fighting is just going to happen, the former of course causing it to happen quickly while the latter takes awhile. Crashing is not totally preventable.
• One thing I've done that I think has helped with the memory issue is that I installed CleanMem, a free memory monitor/cleaner that includes two basic, helpful functions - cleaning your file cache and your memory of unnecessary files. The more often you do it, it seems, the less likely you are to crash. You can also preset it to do it every 5 minutes or less often if you want. Again, my crashing problems haven't been solved by this, but I do think they've reduced due to it.
Personally, ever since I changed my graphics to custom and low on everything, I rarely crash. The lag of recent that was caused by an update has been my only major issue. If you have checked off all my above points, you should have pretty much the same results, especially as available RAM hasn't seemed to be a huge factor in crash likelihood (although, just for reference I have about 7.5 GB usable). Hope this helps.