Try to get the “grey color” of the words to all match. Not too light and not too dark. Don’t leave any space between words and try to make everything the same size and space.
Start the practice session with writing only “i” . Space them close enough as if they are the first and second stroke of an “n”. Do 2 long rows of of these. try to get a long row of grey. Then write a row of “ inu, inu”. Try to make them look like the row of “i”. This is the time to do them very slowly and carefully. Speed is not important; gaining control of pen angle, slant, white space consistency is what you are training for.