You can remove the negative tone of your writing by using ‘and’ instead of ‘but’.
When you write a sentence that uses ‘but’ to join its clauses try changing the ‘but’ to ‘and’ (or another conjunction). It’ll sound more positive.
We all know when someone says, “Yes, but …,” they are disagreeing with us. When we get feedback from someone that follows the “[comment 1] but [comment 2]” we know the ‘but’ is the warning sign.
Sometimes two clauses need to be joined by ‘but’. Most of the time, however, you’ll find that using ‘and’ works just as well.
Sales were up 10% last month but I know we can do better can be changed to sales were up 10% last month and I know we can do better.
Bonus tip: this works in speech just as well as in writing. When your significant other suggests something to you, try starting your reply with: “Yes, and …,” to build on their suggestion, rather than knocking it down.