You've already learned how to determine your ideal training split based on your realistic workout frequency in IDEAL TRAINING SPLIT | How to Train Depending on Your Training Frequency. The next step in getting the most out of your workouts is programming. How should each workout look?
A common theme in all my advice is "it depends on your goals" and "whatever you're able to consistently stick to". There are general rules of thumb I recommend for everyone, especially the general population whose goal is to get stronger and improve overall health. That being said, regardless of your training split, these tips apply.
Here is the magic formula:
WARM-UP. My pre-workout routine takes about 20-minutes to get my body primed and ready to train. No matter what I'm training, I do the same full body warm-up. I prefer bodyweight and banded dynamic stretches and exercises. This is very dependent on YOU and what helps you feel ready to work.
COMPOUNDS. Compound lifts should be the core of every workout. Start every single workout with 2-4 compound lifts, preferably with a barbell. Compound lifts are your "big" lifts like squats, deadlifts, bench press, overhead press, hip thrusts, etc; they call on more than one muscle group. These powerful movements should take up at least half of the workout because they are what your training session should be based around. Take your time on these exercises; push the weight, work hard, and don't be afraid to rest between sets. Supersetting these exercises is not recommended. Keep track of reps, sets, and weight each week to monitor your progress. Getting stronger at compound exercises will translate into increased strength in accessory lifts. Starting with compounds will ensure that your energy is prioritized for the exercises with the most potential for gains.
ACCESSORIES. Accessory exercises are single-muscle movements, things like bicep curls and leg extensions. These exercises come second in importance to compound lifts, but are still beneficial of course! They should be programmed after compound lifts because they require less overall strength and energy and are not the core exercises of the workout. Utilizing training techniques such as super sets and drop sets become appropriate when doing accessory exercises. Isolating muscles is a benefit of accessory exercises, so if there is a specific muscle you want to target, accessory exercises for it will be ideal.
The main takeaways to achieve maximum efficacy from your time in the gym:
Start your workout with compound lifts.
Compound lifts should account for at least 50% of your workout.
Add accessory lifts after compound lifts.