You will see many videos, posts and articles that talk about the “perfect warm up for exercise Y” or the “best warm up for exercise Z”. In truth however, a warm up for any exercise should be individual and specific. No two people are the same and we will each have our own individual areas that need more attention than others, our own specific exercises that we find more effective than others, or even our own specific exercise/warm up routines that may not actually have much physiological benefit, but really get us mentally prepared to lift.
Of course, there are general guidelines that it would be wise to adhere to when warming up for any lift or type of exercise. Quite simply a warm should be no longer than 10-15 minutes, should raise your core temperature, start general and get more specific and include movements that prepare you physically and mentally for the task you are about to perform.
Personally, I avoid foam rolling and static stretching where possible whilst getting ready to lift heavy since this can adversely affect the amount and rate of force production from the muscles. I say “where possible”, because if important contributing muscles are extremely tight or overactive, foam rolling that specific are may be necessary to achieve the desired range of motion and/or avoid injury (although it could be argued if you are that tight in the first place then you may not be recovered enough to lift heavy or need to focus on improving mobility before you start lifting heavy).
Below, is a short video demonstrating a number of exercises that I utilise during my warm up before a squat session. Don’t just aimlessly perform all of them before every squat session. Rather, pick the ones that best target your areas of need and work them into your warm up accordingly.