The above workout may be a little longer than what the average Masters swimmer may be used to, but remember that wearing fins will facilitate your ability to cover more yardage in less amount of time. Swimming farther gives you an opportunity to stay in the water longer and develop endurance while not exhausting your arms prematurely or monopolizing your time.
The Endurance Set of the workout is meant to work your legs, forcing you to kick for a half-mile while not entirely giving your arms a break. While you complete this segment of the workout, concentrate on kicking steadily in small, constant movements. Pay attention to the relationship between your arms and your legs; how many kicks you take per stroke, the rhythm of your turnover, the (hopefully smooth) coordination between your upper and lower body. Lengthen your stroke; you should be taking fewer strokes per lap while wearing the fins than you do without them.
The Main Set is a basic ladder drill, decreasing distance incrementally while increasing effort. The 300 with Hydro Finz should serve to get your heart rate up because it is to be completed at 90 percent effort, but it should also have you huffing and puffing because you are using your legs aggressively throughout the distance.
After the 200 recovery, you should sprint the 100 at 95 percent effort wearing your Zoomers, and for the first time in the workout elevate your body to that high-in-the-water position that comes with racing at elite levels. This will prepare you for the final 100 repeat of the set, without fins, at 100 percent effort. The goal is to beat your previous 95 percent effort time, only this time you will not have your fins. Ideally, you will retain the high-in-the-water feeling that you obtained from your Zoomers and carry it over into that last 100 sprint.
The 500 recovery kick is meant to just loosen your legs and let your heart rate subside before the final 6x50 sprint.
This last set of repeats with Zoomers is just an opportunity to swim fast, use explosive legs, and teach your body to sprint at the end of a workout. The more accustomed you become to sprinting late in the session, the more likely you are to reel in swimmers at the end of a race with your improved speed and endurance.
While the above workout (ideally) alternates between Zoomers and Hydrofinz for various specific drills, it is possible to complete the drills with only one type of fin brand.
It is most important to understand the goal of each set and focus on its purpose as you swim and kick. In time, you will find that swimming with fins is not necessarily an easy way out, but rather a way to improve specific abilities that your competitors may lack.