Among many powerlifters, the theory is that you should try to warm up very little. Warmups are simply tests to spot joint or technique problems that could cause injury at full weight. Anything more is needlessly tiring yourself out before you can get to the heavy lifts that really increase strength.
Intuitively you would expect to lift the most weight in your first set since you are the freshest, the next most weight in your second set, and so on. Also intuitively, if you were to apply your lifts to the "real world" you may not get to warm up.
If you must combine cardio and strength training into one workout, then do the strength training first as you need to be fresh for heavy lifts, and not for cardio.
Note: I'm assuming that you are lifting for strength and doing cardio for heart health. If you're training to become e.g. a competitive runner then this may not be the right advice.
I think I would save stretching for the end of your workout, unless you are very tight, and don't overdo it.