I used to get asked about pain versus soreness, and how to differentiate between the two. And I'd think,
Umm, one's pain. The other is soreness.
But as this question came up repeatedly, I realised things like "listen to your body" and "go based on feel" make sense to me as this is a bandwidth am tuned in to, and you are not.
And that's okay. Just like my eyes glaze over and I understand nothing when my auditor explains things to me, we all have things that we are not that interested in to grasp it fully.
Let's say you have never done squats. And you do 50 squats today. Tomorrow morning, when you wake up, your legs might not work. Your thighs might feel like they are nailed to the mattress. Slowly, you get up and drag yourself around. Feels awful, but you are somehow managing. Then you encounter stairs. Climbing up one flight of stairs seems like the hardest physical activity you've ever done.
That's soreness.
The first day I ever went to a gym and my trainer showed me 6 different machines to work the upper body, I went at it. It felt so good. That pec-dec and the shoulder press and all that. Machines are made to make lifting easy, and I felt amazing. I could not put on my t-shirt the next morning.
That's soreness.
How do you deal with soreness?
Do whatever got you sore.
Even when you become a reasonably experienced lifter, there will be days when you do high volume and/or high load work. And you will be sore the next day. Just do a few sets of free squats (no weights) here and there during the day, and walk around more. That will help in easing the soreness.
I love Pavel's training plans because you do the same thing 3 times a week. Sometimes even 5-6 times a week. Soreness becomes a thing of the past because you keep greasing the groove, and you are repeating whatever got you sore.
A proper warmup, and focus on recovery (stretching, sleeping) should take care of soreness. Even if you feel a bit sore, once you go into the gym and do these, it should ease up.
You might need to keep things at 75% or 50% if you are still sore and not feeling great. But move around. It will get better.
And as you keep getting more experienced, you'll learn to listen to your body better.
Remember, soreness is not necessarily an indicator of anything i.e. more sore is not a better workout.