First actual workout in like 8 months - any tips for stepping it up?

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Amazingly, I'm not super sore this morning - either seems promising or like maybe I need to push it a little harder next time...

Here's what I did:

1 mile run/walk (4.5mph/3.5mph) on the treadmill then 3 sets each of bench, leg extensions, abs, and squats (I have a multi-station home gym) with about a minute of walking in between each set.

Total time: 35 min.
Calorie burn based on HRM: 374

I did make it 3.5 minutes running (in a row!) on my first go, which is better than I did the last time I started a workout regimen (around this time last year :-/).

Anyone have any tips for a good (free) program to follow or want to share what you usually do?