Many lifters are not systematic about attempting personal record (PR) lifts during their regular training. They will often try for a personal best on the spur of the moment because they feel strong that day.
This approach may result in a good lift, but being systematic about preparing for a PR attempt could yield a much better result.
Here is an approach to trying PRs in training that will consistently give you good results.
Treat PR attempts as if you were going to be in a meet. This involves planning in advance so that you give yourself every chance to do your best. Improvising at the last minute, or doing a PR just because you feel strong on a given day will not give you any consistently good results.
First, schedule your PR attempt at least a week in advance. Plan to do PRs following a day of rest.
Begin by planning for three heavy lifts: 1st attempt at 90% of your max, followed by an attempt that will be a PR. You can then do a 3rd and 4th attempts if you wish. Plan the weighs you will use on the first three attempts at least one day in advance. If the third attempt goes well, you can try another increase on your 4th attempt.
Plan what warm up sequence you will use to be ready for the first attempt.
You should also arrange for spotters if you need them. Always have one for the bench press, and if you dont lift in a power cage, you will need a spotter (or spotters) for the squat.
Arrange for someone to act as a referee to ensure that you do a legal lift.
Check your equipment if you are lifting with support gear.
Have chalk available for your deadlift. Chalk on other lifts is optional.
Finally, get a solid nights sleep the night before and two nights before your attempts. You will be amazed how important this is. Sleeping well two nights before your max attempts is almost more important than how you sleep the night before.
Visualize how a perfect lift will feel when you do it. Do this mental rehearsal at least a dozen times in the two days before your attempt.
Day of the PR attempt(s)
When you are going for PRs, you should do these lifts at the beginning of your workout to have the maximum energy available. You also want to conserve your energy for lifting and not dissipate it doing unnecessary work.
Prepare for the first PR attempt by doing necessary warm ups. I always advocate doing the absolute minimum amount of warming up, as a bunch of light reps can sap your strength.
As trivial as it might seem, you may want to ask someone to load the bars for you when you during the PR attempts.
It is important that you practice doing minimal warm ups for at least three weeks before using that approach in a PR attempt. It takes practice to develop the skill of being ready to go full blast after doing minimal warming up.
With warm ups completed, you are ready for your first attempt. This should be a weight that is 85-90% of your max.
When that lift is done successfully, rest three to five minutes (or more) before your second attempt.
your second attempt should be for the PR.
Follow this with another rest period, and do a third (or a fourth) attempt. It all depends on how you feel.
If you are trying for PRs in more than one lift, you should follow your first PR attempts (eg. bench press) with your next set of PR attempts (eg. Squat). Be sure to allow enough time for your body to recover from the first group of lifts before warming up for the second, etc.
At the conclusion of all your PR attempts, you will probably be tired. You may want to do a scaled back version of your regular workout.
I constantly stress the importance of detailed written records. This is especially true in the case of your PR attempts.
You should record every warm up, rest interval and attempt. Make notes about what went right and what you may want to change next time.
Never attempt to rely on your memory. Write it down so there is no question what happened during your PR attempts. This information will be very important to you as you continue to progress.