You are definitely doing well for starting out!! Looks like you have an excellent grasp of space and proportion. That's huge. Kudos to you!! Nice work.
You need more than just one type of pencil. There are all types of leads. The softer the lead, the darker the mark it makes. Using variations of pencils will help you achieve more highlights and shadows with smoother transitions.
If the kneaded eraser wasn't picking up the pencil marks, you were prob using too hard of a lead for that trick to work. If you use charcoal pencils or ebony pencil it will pick up easier, but those are so soft that it's hard to get a lot of detail with them.
Aside from having the right "tack" to create your drawings, it just takes time and feel. There really aren't a lot of tricks to improve your skill, but there are techniques to ea media. It's more about overriding your brain and using your eye. And practice. The more you do the looser and more natural it will feel. Don't get too caught up in trying to recreate every reflection or detail. Sometimes too much detail flattens out a picture and it's a common pitfall when first starting.
Keep it up! You do nice work.
It's a lot like nuts and bolts - if the rider's nuts, the horse bolts! ~Nicholas Evans