I suppose it depends on your stage in life. Dating over the age of forty, for example, is very different than dating when younger. That said, there's one rule that you must follow when dating.

Never tell a lie.

Now, this isn't saying that one should be a saint. There are practical reasons for this rule. A good relationship, or even a fun fling, requires a level of communication and trust. If your partner can't trust you, or if you can't trust them, then any attempt at communication fails, and every interaction has to be played like the dating equivalent of the prisoner's dilemma.

Sample interaction.

"Were you just checking out the waiter's ass?"

Now, we've been conditioned by society to tell a polite lie in this case. The problem is that the other person won't really believe you. By giving an honest answer, you establish trust and open up new lines of communication. What was attractive about the waiter? What can your partner do to be more attractive? What do you like about your partner that isn't what you liked about the waiter?

How abut another one?

"Does this dress make me look fat?"

This one is tricky because, for most of us guys, we have no idea and we don't care. We're running late anyways. Still, the "appropriate" answer is to tell a white lie and go on about your day. What if you were honest? It's an unflattering look. By being honest you have established trust, and can now have discussions about what they can do to be more attractive to you...and what you can do to be more attractive to them.

The point is, you have to be honest all the time about everything if you want to have good dates. If they can't handle you being honest, then it's not a relationship that's going to work out in the long run.