Summarize this article in one sentence.
The takeoff foot is the one that hits the takeoff board; it is the foot you jump off the board with. Generally, a right-handed long jumper takes off with the left foot. New jumpers can try both styles to see which works best.  To determine your takeoff foot, have a friend gently push you from behind. The foot you step forward from is your dominant foot and can be used for the takeoff. Alternatively, you can determine your takeoff foot by thinking about which foot you kick with or which foot leads when you jump over something, such as a hurdle. Practice your run-up several times to determine how many strides you'll take before performing the jump. Generally, the number of strides corresponds to your age, for example:  10 years = 10-11 strides 11 years = 10-12 strides 12 years = 11-13 strides 13 years = 12-14 strides 14 years = 13-15 strides 15 years = 14-16 strides 16 years = 15-17 strides 17 years = 15-21 strides To discover the starting point for your jump, start with your back to the sand pit at the point you will jump from. Run toward the area you generally start from, but only run the same number of strides you have determined you will take before jumping. The spot where you end your last stride is your starting point. Do this several times and adjust your starting point if necessary.  Another way to determine your starting point is to begin from a certain point on the track and run forward the number of strides you have determined you will take. Mark the point of your last stride. Do this several times so you can find an average distance based on the number of strides you take. You'll need to use visible markers that will stand out from other jumpers who have a similar starting point. You can put cones, small flags, brightly colored rocks, or colored tape at your starting point. Place them off to the side of the track so they don't get in the way of jumpers or people competing in other events.

Summary:
Decide which foot you will take off with. Figure out the number of strides you will take. Determine your starting point. Place markers at your starting point.