Relax. Don't be so hard on yourself. You're still new to all of this. You said it yourself.
Hopefully we can help you as there's a wealth of knowledge here. But every teacher is different in their style, method, and knowledge.
I can give you general techniques to diagnose and to understand what you are looking at. The finer details, you'll have to fill in on your own, as they cannot be put into words.
Im going to assume the problem you are having is with gel polish, and not acrylic, but some of the foundation is interchangeable.
Im going to split the techniques into 3 parts. Lifting is quite complicated. Keep in mind, this is limited to what I know.
1. Nail Tech techniques
What a tech does will affect how well the product will stay on the nail. For example:
-applying product over cuticle residue that hasn't been removed. This is probably the number one reason for lifting.
-bad polishing/application techniques. good technique will apply product on effortlessly and smoothly. Not applying the product on properly will create small air pockets in the shape of waves that will eventually lead lifting.
-making the nails too thin from removing more than 5% of the nails thickness
-not cleaning the nail well enough with a good acetone, wiping instead of scrubbing.
2. Client side
Sometimes, a product is simply not suited for a client. But this is rare, to place a number on it, maybe 1 or 2 out of 10 is not suited for the product. Why? It may be that their nails are too thin and weak. Gel polish lift a lot more on on naturally thin nails. Or, it may be that their lifestyle is too hard on the product(constantly bombarded with force)
3. Product side
This is probably everyone's favorite. And probably the most controversial topic. Also complicated. The reason for a wide range of opinion is due to wide range of experiences. But still, its important that we extract the facts out from the soup.
What you need from a product is the following:
1. does not burn when curing
2. cures 90%
3. able to come off with the need to pry, causing noticeable pieces of nail to come off, leaving visible damage spots that isn't reversible when moisturized.
Since the nail tech cannot see if the product cures 90% all the way through, that left with taking the words of the manufacturer. Since we are limited to this, it is therefore fine to make assumptions based on our own internal metrics. For me, my confidence is in CND to be able to do all of these things. Therefore, using a product other than CND is asking for trouble.