The Pareto Principle (also known as the 80/20 rule) states that in most cases, 80 percent of the effect can be explained by 20 percent of the cause.
To put it another way, 80% of our time should be spent focusing on the 20% that is really important.
In sales, this can be seen very clearly. 80% of business comes from 20% of the clients. It really pays a person with a client relationship to periodically stop doing business with all but 20% of their book. This is easy to see in sales. There are clear numbers to guide a person to the right 20%. If nothing else, they should eliminate the bottom 20%. Most don't do this as they care about their clients and it would be unfair. But we can do it in other activities. Eliminate the 20% that doesn't gain anything.
There is not such a clear relationship with backpacking. As I've said in the past 80% is good enough. It will produce about 90% of the results a person is capable of. To get from 90% to 100% is very difficult. This is obvious in writing. To go from pretty good to perfect is very time consuming.
I didn't know where I was going with this, so I did dishes. I was thinking about the 20% that causes 80% of the difficulties while backpacking.
1. Carrying too much weight.
2. Not knowing how to use gear.
3. Planning too much distance.
People think "Ultralight" backpacking costs more. Maybe to go very ultralight does. But a lightweight pack is more about things that are left home than things that are in the pack. It pays to invest in a reasonably good sleeping bag and a tent that won't leak or blow down. These can't be bought in the box stores. The ones that are close are the same price as a place like REI.
So, the first thing I'll do since gear is unimportant is to give a gear list. Huh? The idea is to take the pressure off gear selection. Substitutions can be made, especially in clothes. If a person is unable to afford reasonable quality gear right off, I'd suggest camping with day hikes instead of backpacking. Camping can be almost come as you are. You don't even need a tent if you are near the car. Sleep on the ground and use the car if it rains.
Here is a sample pack I put together. It weighs 27 pounds for a 3 night/4 day trip including food and a full gallon of water. It's expensive, but not a LOT more than buying things at the box stores. Consider this list a guide. I wouldn't suggest a heavier cheaper substitute for most things. The point is not to waste a lot of time endlessly studying which gear to get. This will all work just fine.
The next part is getting familiar with the gear. The simplest way is a few trips to the backyard. Then I'd suggest car camping a couple of times using the gear or short backpacking trips of just a couple miles each way.
Disclaimer: There are a lot of safety issues to learn. They are difficult to learn until you've been out there. Keep the first couple of trips simple and then you will know what to look for in your research.