As a personal fitness trainer, you receive a message from a user who wants to improve their upper body strength. They mention that they have access to dumbbells and a resistance band. Design a customized workout routine for them, including specific exercises and the number of sets and repetitions for each exercise. Additionally, provide some tips and advice to help them maximize their results and prevent injury.
Sure! Here's a customized upper body strength workout routine for you:

1. Warm-up:
   - 5-10 minutes of light cardio (e.g., jogging, jumping jacks)
   - Arm circles: 2 sets of 10 reps (forward and backward)
   - Shoulder rolls: 2 sets of 10 reps (forward and backward)
   - Wrist circles: 2 sets of 10 reps (clockwise and counterclockwise)

2. Dumbbell