Job switch preparation strategy

I've been working in a startup which used to be productive (*years) but not recently (*months). Planning to switch, but there are few problems associated with the preparation. I had to manage multiple teams involving unrealistic deadlines and expectations, leading to forceful non standard practices.

I'm willing to spend sufficient time for preparation despite constant overtime work. I would like to get back into a better work environment both mental and professional.

Concepts that I should be focusing on to prepare for SDE 2 along with resource suggestions are greatly appreciated. (Max time to switch: 3 months)

A list of companies with positive WLB will be of best help.

Let's make this thread helpful for all the potential devs who are stuck in a toxic environment and can use this as a guideline for a fresh positive start.