Fun and Fitness: Spotting can make a difference
The lifter should clarify the following details in order to receive an optimal spot. Are you doing an alternate form of an exercise? How many repetitions are you attempting? Is this a max attempt or a new weight for you? Will you need help lifting or readying the weights into position? When should the spotter help you ready the weights (ex. count to three)? How should the spotter assist you with this? Where should the spotter keep his or her hands and body during the lift? Exactly when should the spotter assist you? Lastly, as the lifter, always tell the spotter if there was anything you didn't like at the end of a lift.
Mistakes are bound to happen, especially with a novice spotter. Let's use the free weight chest press for example. As a spotter, never jerk the weight off the stand trying to prove how strong you are. You'll most likely ruin the exercise all together by throwing off the lifter's steady concentrated position. You want to clear the j-hooks on the bench and give a smooth transitional handoff. Never dump the weight on the lifter. This means you lifted most the weight and simply dumped it off. When giving a lift off, the lifter should still be doing most the work. Help it out smoothly, give it a second or so and gradually let go. Remember you're the SPOTTER, you're NOT the person doing the workout.
There is an important rule of thumb to follow throughout the duration of the exercise. As a spotter, you should avoid hovering your hands under the bar / weights unless you're specifically asked to while the reps take place. If the lifter needs you to do this, then the weight is probably too heavy to begin with. You should never have to touch the bar until the person begins failing. This is a sure way to piss off the lifter if you do so prematurely. Just because he or she is slowing down doesn't mean its time to help. Let them work. Keep in mind some lifters may want you to help them perform forced repetitions to get the best out of their set.
For the most part however, a suitable spot just requires common sense. Yet, it's not common knowledge to the beginner trainer and can be an intimidating task. Some spots, such as for heavy squat exercises require advanced techniques and preferably similar size in spotter/lifter. Such an exercise can even benefit from two spotters on each side of the bar but requires even more communication and precaution from all parties.
Last but not least, be a motivational spotter! Don't just stand there like a mannequin going through the technical motions. Cheer them on, encourage them on how well they are doing and yell at them to do one more if you know they got some left inside! It's those last couple repetitions before a lifter reaches failure that make the difference. Be THAT spotter, be THAT difference!