Exactly cal im the same way always reading and trying to improve my knowledge about it. Trouble is you read so much it does get confusing and crossed up with some saying this and others saying that you have to sort it all out. I looked into advanced nutrients but I thought they were all specifically for hydroponics and I didn't have a hydro setup....yet...lol. I've read some about using coco coir but I didn't have any xp in that and I wanted to be able to get a few nugs my first time out.
Dude trust me I feel your pain. YouTube is very debatable because lots of footage you watch there is going to be marketing and always have a catch to it. Advanced Nutrients works in any growing medium or hydroponic setup. You just mix into your water then feed into the pot.
If you want big yields I found that growing in Coco with those nutrients was the easiest and best so far.. I've tried the full-line of their bottles and yeah you get a bit better yields but the quality doesn't improve it actually decreases in potency. I'm a medical & rec smoker so I consume easily an 8th of weed per/day to myself on average. That is with strong marijuana. When I get some stuff from a friend that looks great I usually have to smoke an entire joint at once to even get an effect. Upsetting!
Always remember that the more quantity you have the quality does deteriorate. I've proven this with a fellow grower that has been growing for 10 years. The longer you veg plants for example (30 days vs 60 days) the 30 day plant is almost always going to yield less but be danker and the 60 day plant is going to be bigger yield more but be weaker and less tasty.
Experimenting is the best thing you can do and always start from the bottom up. e.g just use the base of a product and add things as you get more comfortable. Life's a garden, dig it and enjoy!