I am trying to gain strength, which leaves a lot of rest time in between sets (3-5 minutes). I am a beginner and have no clue what to do in between sets! I kind of just dag around. What are some decent things to do in between sets?
If you're goal is strength than in between sets you should rest. Catch your breath. Have some water. Nibble on some sort of calories. Load more weight on the bar. Then go again. Not sure why you're waiting 3 to 5 minutes between sets as a beginner unless its training with partner / partners that are going in that time. In which case help them load their weight, watch what they're doing, and relax.
Relax. Sit, lie down, listen to music, talk to friends. If you're outside, enjoy the sun. If you really want to do something related to the training, visualize the exercise you are doing.
Where do you get the idea, that you have to fill your time? Actually, if you fill your time between sets with random stuff, you lose mental focus on your training.
One word: cardio. Do anaerobic and aerobic routines.
Between deadlifts I would do sprints and running and hurdles, combined with playing soccer.
When I would finish there I'd go catch my breath in 10 seconds or so and then get back at it.
The key point here is that, even if you're "resting" between sets, you can keep doing other stuff.
If you're resting from sets on the bench press, do pull ups or chin ups inbetween.
If you're resting from pulls ups/chin ups, do dips or squats; or just run around like a sneols.
Point is, even when resting, some part of your body/system can always keep working.