A wise man (I believe it was Mark Twain) once said something like "It is much easier to tell the truth. There is much less to remember." A simplistic approach to honesty but true.
I remember being probably no more than 10 years old when I decided honesty is the best policy. I was walking down the street thinking about something and it just clicked. Ever since then I've tried to be honest. Sometimes I have failed - more often than I'd like to admit. Sometimes I have been too honest and offended or hurt someone but I think this is better than having lied. A psychiatrist once tested me and said I was too honest. This makes me wonder about the society that produced this man and what the implications are. Does what he said bother you? It should.
If you lie you must remember not only the lie and the truth but who you have lied to and who you have not. If you have created multiple lies about a situation and told different people these different lies then you must remember what you said to whom and keep them from talking to each other. Your life becomes convoluted and tortuous and the more you lie the more difficult it becomes to remember everything. What kind of a way to live is that? Is it worth the stress? I don't think so.
Personally, I think it is much better to be honest, simply because you are then trustworthy. People may not always appreciate when you are honest because sometimes the truth has a way of slapping people and making them realize their shortcomings but it is far better to deal with someone honestly than to constantly deceive them with words and deeds. People know they can come to you when they need someone to be honest with them. This doesn't mean you have to lose all sense of diplomacy. Some people simply cannot handle the blunt truth. But the fact remains that the truth is always the best course of action. Do I always tell the truth? No, but I try to. Does anyone always tell the truth? I highly doubt it. When your friend, highly distraught, comes to you and asks if they are attractive and they aren't but you know that at that point it will crush them utterly to tell the truth do you? This is not an excuse merely an example of a time when it is best to sidestep. Don't answer falsely but try not to answer at all. Return the question to them. "Do you think you're attractive?" Or, taken from a different approach, you can read deeper into their question than they might mean. Take into account their personality, their heart, their soul. Are they attractive on the inside? Then you can honestly answer "Yes" to their question. Beauty is not just skin deep. Beauty is what is inside and outside. It's too bad that it's rare to find someone who is beautiful inside and out.
Just remember the best way to teach most people is by answering their questions with questions. Find out what they think and then ask questions that will lead them to discover your point of view without you having to say it. If they work through the logic of your questions themselves and arrive at the conclusion you already know they are much more likely to accept it than if you simply tell them.