Yes, I’ve read Monroe’s books when I was 18.
They were very helpful.
But the techniques that got me out of body the first time where from the book “Out of Body” by William Buhlmann, which in my opinion is still the best entry book for this topic.
I’ve read this book right after the Monroe trilogy and then it took me 3 months of daily practice but was totally worth it and a completely life changing experience.
Just focus on a daily practice like e.g. before falling asleep every day and sooner or later it will work.
Persistence is key here.
I never tried the Gateway tapes as I didn’t want to learn the skill with being dependant on external tech. I also could never relax my body with headphones on my head.
Check out the Astral Travel Thread, there is a lot of great info there: