When you can, group bugs for investigation
While I wouldn't normally consider this a "quick testing tip," on some teams testers also help with initial defect investigation to help identify root cause. If that's the case, and you're one of the testers who works with a production support team to isolate and more clearly define (and fix) production bugs, then this tip is for you.
Before you pull a bug off the top of the stack for investigation, do a quick search to make sure there aren't similar issues in the backlog that should be investigated at the same time. I've found that if you're looking for three similar issues when trying to recreate a similar set of problems, that you can make headway (on some of them) faster than others. It's also possible that simply by looking at how the bugs are clustering, you might gain better insight into what you'll need to do to recreate or isolate them.
Before you pull a bug off the top of the stack for investigation, do a quick search to make sure there aren't similar issues in the backlog that should be investigated at the same time. I've found that if you're looking for three similar issues when trying to recreate a similar set of problems, that you can make headway (on some of them) faster than others. It's also possible that simply by looking at how the bugs are clustering, you might gain better insight into what you'll need to do to recreate or isolate them.