For many years now, I've lived by the following standards:
1. Communicate with others when you need something.
2. Be honest when you're trying to resolve an issue. BUT... you need to be polite about it.
When we're kids, many of us are taught that honesty is the best policy. By being honest, you get straight to the point, and even if you end up in trouble over it, at least you can take immediate steps to rectify the situation. As you grow older, people will be able to respect and trust you more if you're honest and straight to the point. Consider this: when in a job or classroom setting, you're responsible for showing up on time and meeting deadlines. Chances are, there will be one time that you mess up "on the job" and will need to talk to someone in charge. As long as you are honest about what happened, your boss or professor will likely be forgiving.
However, honesty doesn't only apply to the professional world. As a young adult in college, I find honesty especially important when communicating with my peers. There will be times when your friends make a mistake and upset you. Of course, you'll expect them to own up to it, but they won't always know what they did wrong unless you bring it to their attention. If you value a person's friendship, you should be able to take and receive constructive criticism.
And that's the key thing: you need to be constructive. Often times what happens is people get overwhelmed with their feelings and they won't go about resolving the problem the right way. When you're discussing a problem you had with a friend, you don't want to come across as rude. Always be direct, but before you talk with the other person, think about what you are going to say. If you wouldn't want it said to you, then it's likely best to reword something. Most people are open to honest feedback, but you should always be civil. There's a good chance they genuinely made a mistake, so try and treat it as such. Just remain calm, and if people care enough, they will listen to you.
Just remember this: it isn't always about what you say, how you say it makes all the difference.