If you haven't made progress in a while.....

• Make sure you're sleeping enough.  Sleep is the most natural form of recovery.  Remember that you dig "sleep holes".  In other words, if 8 hours is ideal and you get 6 hours one night and 8 hours the next.  You're still 2 hours in the hole.  Try to make sure that you get the full 8-9 each night.  If you don't require that much just make sure you are hitting your minimum.  Try not to use an alarm clock and go to sleep early enough that you wake up naturally at the right time.  
• Take time off until you are itching to lift again.  I don't do planned deloads.  However if my zest for training starts to wane, I just take enough time off to recharge until I want to lift again really badly.  
• Drink more than a gallon of water each day.  I have no idea with everything we know now, that people still don't drink enough water that lift and condition.  Keep drinking well after you are done with a training session too.  This can't be stressed enough.  Make sure to have at least 2 clear pisses within an hour after you are done.  
• If you do take time off, when you come back, start light and don't do a bunch of shit.  One of the things that drives guys into the ground is that when they feel good, they do everything under the sun.  When the lifts start climbing, they keep trying to do everything.  Something has to give at some point.  So just pick 1 or 2 big movements per session and 1 small one, or 1 big one and 2 small ones.  Stay simple.
• If you've been training high volume for a long time, take a week off and go high intensity for the next 6 weeks.  If you've been training high intensity for a long time, take a week off and go high volume for the next 6 weeks.  
• Squat and deadlift on the same day.  1 heavy and 1 light, alternating each week.  I can't break these up anymore.  Everytime I have I get run into the ground.  
• Cruise on the lifts until you feel yourself getting stronger.  This WILL happen.  This is the smart, patient mans way to train.  Steady wins the race.
• If you are a REALLY skinny guy trying to gain weight, eat every 3 hours as much as you can.  Lots of everything.  Protein, fat, carbs, everything. 
• If you are a fat guy be mindful of the weekends.  This is when you will tend to overeat by as much as 20%.
• If your deadlift has been stuck and your technique is good, then get your upperback strong and jacked as hell.  Lots of t-bars, barbell, and db rows.  Shrugs, chins, and pulldowns.  Keep deadlifting, but push up your weight and reps on all of the big back movements.  
• If you squat has been stuck follow up squatting with a really quad dominant movement like hacks, fronts, or leg press for high reps.  
• If your bench has been stuck......gain 10 pounds.
• Use rest/pause and concentrate on beating those total reps each week.  
• Do some bodybuilding for a while.  Lots of powerlifters do this and come back stronger.  Probably because they just needed to get stronger in some areas that had been neglected.  Usually calves, pecs, arms, delts, etc.  This is because some powerlifters often spend too much time now worrying far too damn much about hamstrings and triceps.  Strengthen your whole body, get big everywhere.  Spend some time doing flyes, laterals, curls, forearm work, etc.  I am all for limited training but there is a time and place for bodybuilding and when you need a boost in mass and strength, do it.  
• If you are a bodybuilder and have been stuck for a while, do some powerlifting and get stronger.  When you go back to your medium and high rep work you'll be able to handle more poundage there.  This means more mass.  Powerlifting and bodybuilding both have training ideas that lend help to one another.  
• Pick something show up for.  A meet, a bodybuilding contest, take up a new sport, do something that makes you show up to perform.  If you haven't ever done this, it will drive your training like never before.