Form is always the most important thing to focus on in a workout. It protects you from injury and gives you better results faster! As a fitness instructor I often see many struggle to get form correct. Most likely because they learned it wrong in the first place and no one bothered to correct them. They say it takes 1,000 reps to learn something correctly and 3,000 reps to correct! Might as well focus on getting it right the first time :)
Squats-
1. Make sure your weight is in heels, you should be able to wiggle your toes as a test
2. Knees should track BEHIND toes, push your butt back like you are looking for a chair
3. Relax shoulders away from ears
4. You don't have to get to 90 degrees if you have knee issues or are new to fitness. Start with a smaller range of motion and work your way up to a deeper squat!