It would be nice to read some books like Language Implementation Patterns for deeper thoughts after following some easy tutorials. That book is good for designing both DSL and general-purpose languages and explains multiple patterns with pros and cons, tradeoffs, etc.

And also, it's better to check out some metasyntax notations, e.g. EBNF https://en.wikipedia.org/wiki/Extended_Backus%E2%80%93Naur_F...