Workout frequency and exercise selection
Normally, your weight training routine should allow you to train each body-part about twice a week, with two or three days' rest in between workouts. (Between successive workouts for the same body-part, that is.) A sensible long-term fitness routine also requires that you devote equal attention to each major muscle group, perform multiple exercises for every body-part, and vary your workout regularly.
When preparing for a specific lift strength competition, you will (temporarily) train less frequently, (perhaps four or five days between workouts), suspend much of your attention to your other body parts, and focus almost exclusively on the competition lift, in this case, your bench press.
Range of repetition and training intensity
Normally, your target range should be roughly from ten (minimum) or twelve reps per set to about fifteen repetitions. Only by keeping your repetitions well above ten will you be able to get a good "pump", which every bodybuilder knows, (or should know), is the key to muscle growth. In fact, athletes who specifically do NOT want to gain muscular bodyweight (wrestlers, boxers, track competitors, etc.) purposely keep their reps below ten per set. Similarly, when physique shaping, muscle building (or even muscle maintenance) is the goal, your training tempo should be relatively intense, with no more than sixty to ninety seconds' rest or so, between sets. In your long-term fitness routine, the idea is not to allow the muscle being trained to recuperate fully between successive sets. A minute or two of rest is sufficient rest for the muscle to work to the point of productive failure, but not necessarily sufficient for you to handle as much weight as possible during every set.
When preparing for a specific lift strength competition, you will (again, temporarily only), exclusively perform sets of fewer than ten repetitions and allow as much as four or five minutes' rest between your heavier sets. Whereas a bodybuilding (or shaping) routine requires that you keep your reps high and rest only as much as necessary to be able to perform another productive set, strength training dictates that you focus on sets of approximately three to six reps, and rest as long as necessary for (nearly) complete muscular recuperation between sets.
Lifting technique
Normally, your actual lifting technique should maximize the fullest range of motion possible for each exercise, because the idea is to work a muscle equally at every portion of the movement. Similarly, you should strive not to "power through" the point of least leverage (or "sticking point") by generating extra momentum from the range of greatest leverage. When performing an exercise properly, the bar (or dumbell) should move at a uniform speed throughout the entire lift, rather than accelerating explosively like a rocket being launched.
When training for a maximum lift competition, the idea is precisely the opposite: Instead of trying to work the muscles involved in the lift uniformly throughout the range of motion, you will specifically try to generate as much explosive power as possible at the beginning of the lift, precisely to help move the weight past the sticking point, which in the case of the bench press, is normally about halfway up. Instead of positioning your hands at shoulder width to force your elbows as far back as possible to elongate the pectorals at the bottom of the lift and stretch the range of motion, you will take a slightly wider grip, to gain leverage and shorten the distance that the bar must travel before it touches your chest.
Instead of maintaining full contact between the length of your back and the bench to isolate your pectorals, you will arch your back as much as possible without moving your butt off the bench. The reason for this is decline bench presses (where your upper body is angled lower than your torso) are easier than flat bench presses - the same as incline presses are harder than flat presses. By turning the lift into a decline press as much as possible without taking your butt off the bench, you also allow secondary muscles like your lats to assist your pectorals. Finally, instead of touching the bar to the highest point of your breast bone to stretch your elbows as far back as possible, you will touch the bar to the lowest part of your breast bone, which shortens the range of motion even more.
Typical pre-contest workout
Normally, you will want to take every set (after your warm-up sets) to the point of muscular failure from fatigue. Doing a set of twelve reps then, does not mean simply putting the bar back because you reached twelve reps, but choosing a weight properly so that your muscles burn so much by the twelfth rep that you couldn't possibly do another. When training for normal physique development purposes, you will specifically add weight in small enough increments that you can perform almost as many reps on each successive set before muscular failure as on the previous set.
When training for a maximum lift competition, you will specifically avoid reaching the point of muscular failure from fatigue on every set building up to your heaviest set in such a way that for a set of any chosen number of reps, you could do one or two more. You will add weight in larger increments, so that a set of ten is followed, say, by a set of six, and that set by a set of four. It is inadvisable to do a maximum lift more than once every two or three weeks, so your heaviest set should be with a weight you can get a "triple" (three reps), or a "double" (two reps). High level powerlifters usually come to a contest not knowing themselves what their maximum ability is, and from a psychological (as well as physical) perspective, you are more likely to achieve your true maximum lift on the day of your contest if you have not recently handled more weight in training than your heaviest "double" or "triple".
Limited range training
One way of increasing your maximum lift potential is by specifically targeting the "stick point" in the range of motion, another is by working the negative portion of the exercise. One training day each week you can work on your stick point by having a training partner or spotter help you through your stick point, while you do the rest of the reps yourself. After your regular bench press training sets, take a weight that you can lift confidently for a "triple" and have your partner help you get more reps by assisting you only where you get stuck, completing the reps yourself. Also, try doing partial reps with the heaviest weight you can lift (say, from full lockout down a few inches and back up) with the assistance of a partner in case you lower the bar too far and get stuck.
You are always stronger on the negative (lowering) portion of an exercise than on the positive (lifting) portion. One way of getting used to the "feel" of the weight you hope to lift on the day of the contest is by doing negative sets. Load the bar with your maximum weight and have your partner help you raise the weight, lowering it as slowly as possible by yourself. Besides the psychological help of getting used to the weight, this also strengthens your tendons for your eventual maximum lift attempt.
