I think the most important part of training is to understand your body.
Take an extra day off if you feel that you aren’t in an optimal condition to do a lift.
Also, mix up your assistance and your main movements constantly! You have to put your body in a constant state of adaptation. You can then have a 2-3 mesocycle where you can test your 1RM for a particular lift if you feel you are ready. Personally, when going for that new max attempt, anything over 102-105% of your previous 1RM may be a bit overreaching unless your previous warm-up lifts were very quick/easy.
Bar speed is to vital to the deadlift, so always use explosion after creeping down to the bar.
My favorite assistance movement for the deadlift is the rack lockout (pin pull) above the knee, which is where I stall.
It is also of tantamount importance to train the grip in the deadlift, so do them raw and hold the barbell in your hands for as long as possible.
If you are weak off the floor, I would suggest rack squats, another wonderful exercise. When doing rack squats, you should start from the position you start your deadlift in to simulate that same “pulling” distance.
I just want to add that I am a small dude, 5’6" 132 lbs and pull 435 lbs (I will be testing my new 1RM in 3 weeks). I made the mistake of not training grip raw (used straps), so my previous attempt at 445 was lost because of my god damn grip.
Additionally, I feel that the lighter guys doing powerlifting should really focus on their technique and design an intelligent program to suit HIS/HER needs.
The golden rule however is not to train over 90% for more than three consecutive weeks of a single main movement. This will only result in overtraining and cause a regression/set-back in training.
However, TRAIN HEAVY! This may not be the case on your main movement, but those two previous exercises I mentioned before should be trained heavy, as long as not too much volume is performed. I probably do 3-5 reps total; to train the CNS that I can handle this weight during a max effort attempt.
Beginners can use progressive overload to a point, but if you do not see significant gains in your numbers it is time to switch to the ME/DE westside cycles. An additional note regarding progressive overload is that I believe that they should be done in 3-6 (6 weeks being the max) week cycles because any longer would create too much fatigue (in my opinion) and stress on the CNS when training in the last weeks of lets say a 12-week cycle.
Please PM me if you have questions, I am more than glad to help.