Well, that depends on the kind of mistakes you are making. You talk one on one with your players...you sandwich the corrections...Jimmmie, dang you had an awesome tackle on that misdirection they ran...you stayed home, you had great balance and you buried the guy...so fun! I noticed, on the third and two where we didn't stop them...you know the play I mean... ya, all we needed was a better angle, you came up too soon and got buried in the wash....trust your keys, just a half second of patience and then explode downhill once you got your read... I'm excited, you are playing so good....we get every doing their job, buying into their assignment and we are going to be scary good as a unit. Great job! One example...easier with film.
You address it in practice through drills, individual and team. You correct what broke...you don't need to drone on how horrible they were...they know. You just positively speak to fix the breakdowns without making them scared they'll never beat anybody. The whole thing in sports is confidence. Designing schemes that are successful for the people you have to work with. The difference between okay and great is pretty much mindset.
Lots of ways but what you don't do is create doubt. You reassure them we got this. We just need to tweak this. How cool was when it when we forced them to go 3 and out twice in a row? We just gotta string more of those together guys. We can do it, just gotta change our best.
Obviously the coaches spend a lot of time figuring out how to fix things after the fact. You don't share your worries with the team or certainly the media. You address mistakes by what you emphasize in practice for drills. Especially, especially after game one!!!! They are all trying to impress the new coach, looking for a pat on the back. Crushing whatever confidence they had is pretty dumb.
Mental preparation is huge. Talk to guys who wet the bed. Find out where they are at mentally. How'd they prepare BEFORE the game.
It's 5 days after the game and the coach is still talking about mistakes. We had more good plays than bad. But we can sure create or manifest more bad plays if that's what we are going to talk about.