If we had to limit ourselves to 10 adjectives to label the world, it would be a poorer place. Don't feat a larger number of tags; just learn to create them judiciously.
But now some of my notes have no tags associated with them and I don't want to have more than 10 tags (for simplicities sake)
It's not how many tags you have, it's having tags that are easy to remember, easy to use, and to not create multiple tags for the same thing (a "dinner" tag and a "supper" tag)
I use a tag for each of my clients. That's easy because I know their name and so typing in the tag without getting duplicates is easy.
Often, my client's name doesn't appear in the note, so I tag it. I also tag my Code notebook notes with tags like "PHP", "SQL" or "JS" - Because code snippets don't necessarily have the language in them. I also use tags when the topic of the note is a word that is so common It would likely appear in a lot of unrelated notes. "parent" could appear in a lot of notes, so I use a tag "parent" for MY parents. That way I can easily eliminate the notes talking about "parent" and child tags, or news articles about Mrs. Obama's skills as a parent.
The tricks are to not use tags for stuff you can easily search, and to be careful about tags where you could end up with multiple tags for the same thing.
Other than context tags, and client name tags, I have about 10 or 12 tags. I expect it to grow some, because I already have an idea about what tags I will need, but haven't created a note yet on that topic. For example, I don't have a Ruby tag or a Python tag yet. If I had 10 clearly defined contexts, I'd have 10 context tags, but I don't, so I have 3: @grocery @home @work.
Just remember that the idea is to use EN to make your life easier, not to create a bulletproof filing system that you have to constantly think about, reorganize, or remember a lot of stuff to remember how to use it.