Reversing an inputted sentence
I sometimes hear people say how they can distinguish between good and bad coders of a certain programming language or even programming in general simply by looking at the code they write.


I think that's true, to some extent. How else (except by the code they write) would you judge a programmer's ability?

Distinguishing programmers from their code is just the beginning though: see this answer for example.

Professional-level programming might also be categorized e.g. with Programmer Competency Matrix


  I was just wondering whether my program follows best practices


Not all the best practices; it could still be improved, for example:


Avoid macros (#define)
Format it well (use indentation)
Give good user output (better than "Enter something:  ")
Use subroutines (don't put everything in main)
Don't overflow your input buffer (e.g. if the end-user enters more than 10 words, or words more than 20 characters long)
Use library methods appropriately (e.g. not printf("%c" when you want to output a whole string and not just one character)
Use good identifier names (e.g. I'd prefer row and col, or x and y, or imax and jmax, instead of count_1 and count_2)
Be flexible in handling input correctly (e.g. I'd prefer arbitrary-length words and arbitrary-many words, which would require you to use a heap-based list or array of variable/infinite-length strings, instead of a fixed-size array)



  I know the next bit is a bit opinionated, but does my code give an idea of where I'm at with logic and programming as a whole


I think so. The code matches where you said you're at, which is that you are "relearning C".

Working a 40-hour week makes about 2000 hours per year.

So an adult professional programmer will have spent many 1000s of hours of practice and studying.