Always be conscious of your decisions and the long-term effects (or side effects) they may have. You can spend years doing the right things, but if you cut corners or are involved in questionable activities, it can take seconds to ruin your reputation. Once you break that trust, it will always be in the back of that person’s head on if they can trust you again or not. It could literally take a lifetime to repair that trust, but who knows if it will ever happen.
The best way to maintain and strengthen relationships is by thinking about the long-term. Don’t acquiesce to immediate gratification. You might feel pleasure once (in the short-term), but then live with regret for the rest of your life. Do yourself a favor and live with integrity. It will help others to like and trust you, but more importantly, it will allow you to like and trust yourself.