This was shared by one of my students, and I thought it was worthy of being passed on, especially since the advice is proactive and has a basis from an Islamic perspective.
1. Keep skid chains on your tongue; always say less than you think. Cultivate a low, persuasive voice. How you say it counts more than what you say.
2. Make promises sparingly, and keep them faithfully, no matter what it costs.
3. Never let an opportunity pass to say a kind and encouraging word to or about somebody. Praise good work, regardless of who did it. If criticism is needed, criticize helpfully, never spitefully.
4. Be interested in others, their pursuits, their work, their homes and families. Make merry with those who rejoice; with those who weep, mourn. Let everyone you meet, however humble, feel that you regard him as a person of importance.