There's an old saying: Better to keep your mouth closed and be thought a fool than to open it and remove all doubt." There is much debate as to who said this, although Mark Twain and Abraham Lincoln are thrown into that list. Too many times people dig themselves into a whole, so to speak.
There's another Biblical quote that says: "Know what you are talking about before you speak, and give attention to your health before you get sick." (Sirach 18:19) The saying generally refers to the concept that it's better to "examine your conscience before the Lord judges you."
Many times people speak before they think, and often times people form opinions based on opinions rather than facts. If your opinions are based on facts then you'll have the facts to back your opinions up.
Furthermore, "Humble yourself before you are punished with sickness. When you have sinned, show repentance" (Sirach 18:21) The general idea here is that we all go through life as sinners, and we all do things we know we shouldn't do, and we should humble ourselves before it's too late.
If you do something to offend another person, or if you do something stupid, you should apologize and apologize vigorously as soon as you can. This may not forgive your offense, but it will set you on the right path and show you care. It can save your job, and your marriage.
You should apologize even though you think you're in the right. In other words, humble yourself. Of course you can read about this ad nauseum in the Bible, and you can read about it ad nauseum in just about every personal self help book.
Think before you speak. This is easier said when done.
Be frugal. This is also easier said than done. There is so much temptation to spend money on material things today, especially with all the electronic gadgets. Yet I've seen so many of my friends and neighbors lose everything because they couldn't stop spending and borrowing, which is a path Uncle Sam is headed down.
Anyone besides me notice that you can get a TV for basically nothing these days because all the spenders are purchasing one of those new flat screen TVs? Sure they're nice, but those people have put a TV in just about every room in my house, and I've paid only $10 for all of them. They work just fine.
"Every intelligent person can recognize wisdom and will honor anyone who shows it. If you appreciate wisdom when you hear it, you will become wise yourself, and your words will be a source of wisdom for others." (Sirach 18:28-29)
Read, read, and then read some more. Too many people think they know so much. I used to think I knew so much too, and then I started reading and realized I know so little. Surely reading is humbling.
Every person can be wise who chooses to be wise.