I started rucking 3 years ago. Start light - I remember carrying 10lb weight would take a lot out of me. At one point I was doing 50 lbs over approximately 7 miles (1hour, 45mins total) with a few breaks in between.
However, I "acquired" a few issues to include early arthritis and potential meniscus issue in my knees. As a result, I started "rucking" with a lightweight pack carrying no more than 5-10 lbs.
When it comes to packs, I tried Mystery Ranch NICE framed pack. I find that to be overkill and the waist belt too stiff. My go to pack (the one that I also used for 50lb) became Camelbak TriZip.
If using plates in backpacks, having a pocket that can fit a weight plate is highly recommended.
When carrying anything over 15 lbs, I recommend a waist belt.
I also read that others people use water bladders for weight. After a certain point in the hike, empty it, changing the load.
For weights, I went with Titan Fitness - they were cheaper than Goruck.