Supersets are great, compound sets aren't as great for muscular strength and size gains.
Supersets are two back to back sets, each exercise an opposing muscle group. Example:
- Incline Bench superset Bent Over Rows
- Front Squats superset Romanian Deadlifts
- Hammer Curls superset Rope Pressdowns
- Hip Abduction superset Hip Adduction
Supersets are great because working opposite muscle groups back to back increase strength in the second exercise IIRC. So if you normally do rope pressdowns with 110 lbs doing hammer curls before them might allow you to do 115 lbs for the same number of reps.
Compound sets are two exercises that work the same muscle groups back to back. Examples:
- Flat DB press superset Flat DB flies
- Front Squats superset Leg Extensions
- Pulldowns superset DB Pullovers
Seated Calf Raise superset Donkey Calf Raise
This weakens your strength in your second exercise, so if you do more than one compound set your strength will drop on your 2nd, 3rd, and so on sets.
Compound sets have their place, but supersets are better IMO for progressive overload which is crucial for long term strength and size gains.
Now, for your routine, Id recommend an upper lower to start out with. Save the Arnold routine for when you're more advanced