My first thought was the fabric also. Test your machine on quilters cotton to see if that is the issue. I would use a tear-away double layer light weight or one layer of medium weight for you test. If you don't have the tear-away, you can use a medium cut-away. This is just for testing.
When I started embroidery, the one hour free lesson provided by my dealer just wasn't enough. It's been a few years, but I found Craftsy.com to be a good place to learn about machine embroidery. They have classes on thread, stabilizers, and how to embroidery different types of items. The classes are much more in-depth than you-tube type classes. I am still a subscriber so I can't get the offer, but I have read that they are offering 1 year membership for new members to view all of the videos for $3.
Have fun and enjoy the learning curve. It's worth it.