I am a very straightforward person that has severe trouble conveying things indirectly, tactfully or basic lying. Need help especially navigating difficult corporate conversations, where all of these are required almost everyday.

I have now obtained a basic understanding of what people actually mean when they say something else. But I'm still struggling to say something when I mean something else. Most people find it intuitive, but I'm not there yet.

A basic example - lots of people easily say "I'll call you tomorrow" even when they have absolutely no intention of calling later just to push off people. I am the dumb guy that would directly say "No, sorry, that's not possible" and it's making my life so much harder. I need to change.

General guidance on the approach would be awesome. I would also love getting feedback on my wording and specific approach in some important mails and phone calls. Whichever you can help with.