A person may start to change quickly by doing or increasing certain acts such as salah or sadaqah. Or stopping certain things such as going to pubs or gambling.
The hard part is changing the akhlaq (manners) which have been ingrained by daily habits for years. He may continue to talk dirty, tell little lies, backbite, look down on others, argue, debate, etc.
A significant improvement to your akhlaq can be achieved by avoiding argument.
Knowing and applying this hadith 1 would definitely help. Avoiding arguing with another person isn’t something that’s easy to do., especially when you’re in the right. Doing this is very commendable and a great reward (Paradise) awaits the doer.
Arguing with someone is a useless and risky thing. Win or lose, it only creates bad feelings between both sides, and this is a major cause of damaged relationship among people.
Just say what you want, and then keep quiet. If the other person responds negatively, just keep quiet. Have sabr.
So, avoid arguing. This is not an easy thing to do, but the reward is so great. Both in your Akhirah, as well as the Dunya now.