I always knew Tony was a shytty person, but this thread is the first time I realized how much of a shytty boss he was.
He constantly ignored the crew's problems, put himself before everybody else, made decisions that put people in danger, and disregarded how important loyalty was. You could argue he killed Gigi by making him captain instead of Ralph because the stress was too much for him.
To answer the original question, if I was Tony, there are a couple of three things I would have done differently:
1. Never beaten Zellman in front of Irina. Tony was just upset because Irina was happy with someone else when he didn't want to be with her anyway. She ended up telling Carmela about Svetlana out of revenge, which led to the separation. If Tony never shows up to Zellman's house that night, Irina never calls the house.
2. Give Tony B up. I know he was trying to protect him from Phil, but nobody in the crew was with him on that. Tony B cost them money (Vespa scooters, imported provolone) and guys in the crew were getting assaulted for nothing (Benny). I'm pretty sure Vito threatened to kill Tony because of how far things had been taken. The war with New York might have still happened, but this was one of Tony's biggest mistakes.
3. Supported Chris in the last two seasons. Guy was obviously sensitive about being sober and unable to hang out as much, and all Tony did was criticize him. He was the one that pushed him to get clean and resented him for it. He was five seconds away from sleeping with Adriana and implied that even if he didn't do it, Christopher wasn't good enough anyway. Chose Tony B over him. Showed no sympathy after Adriana died and made it seem like Chris had to get over it. Tony blew up a perfectly good relationship for no reason and drove Christopher to make that movie. He stopped looking at Chris as family and started looking at him as an enemy. He could have used him in the war with New York.
A lot of Tony's struggles came because he dumbed himself out of position. He was never a great boss, but he just got worse over time. Jackie would have died twice if he saw what Tony turned into.