If I had to reccomend one exercise for anyone to do this is it.
For general strength and postural stability the body weighted squat is the absolute essential for any training program, or at least to nail as your progress up to more difficult exercises.
This compound movement has a high degree of relevance to day to day life is particularly good for people who require a lot of lifting in their professions, and anyone looking to improve performance in most sports.
Once your technique is flawless move on to weighted squats but ensure that you can perform this movement well and that you are placing emphasis on the correct muscles groups.
The muscles groups this exercise should focus on are: quadriceps and glutes. This exercise will also benefit your core muscles and lower back.