You are going to force people to respect you? You can't do that, even the Buddha couldn't do that. The Buddha could not force anyone to respect him. He convinced people to respect him. One really cute story shows this, the Canki Sutta. If you haven't gotten the 20 Suttas that we have as an email word document attachment, it is one of the 20 Suttas in there, the Canki Sutta.
The Buddha comes to this particular village where the head Brahmin priest of the village, was named Canki - so that is where the name of the Sutta comes from. The Buddha was staying outside the village, which was his normal thing to do, and a lot of the Brahmin priests just happened to have a convention at the town at that time. About 500 of them were there. They heard the Buddha was there and they went out to greet him. Some of them had met him before and said he was a good guy, so the Brahmins decided to see what the Buddha had to say.
They go to see them and as the Buddha was talking with one particular older priest, a young priest kept butting in. He was only 16 years old and he kept butting in. The Buddha says to him, "You are not keeping your place, little guy." (Different words, of course) Yet Canki says to the Buddha, "Oh, but Sir, young so and so is very equipped to debate with the Buddha equal to the rest of us." So the Buddha understood this and he also perceived with his own psychic abilities that the young fellow was really very highly respected amongst all the older people, because he had learned everything so quickly and was so bright.
So the Buddha then discussed a bit of teaching with the young fellow. As he was discussing just with the young fellow back and forth, what was also happening is that 500 other people were listening, right? All the other priests were listening. Now a lot of them didn't like the Buddha and the young Brahmin priest in particular, I think he said something like, "Ah, I used to think you and all of your disciples were just stupid, idiot, shaven headed, feet of a kinsmen." I don't know, something like that. The lowest of the lowest, he actually explains to the Buddha that that is what he used to think of them.
But now because of what the Buddha taught him during that interchange he developed so much respect that he said, "Now I have deep respect for you, and for the Dhamma and the Sangha, and I am very happy." In that interchange, of course, the Buddha was not just teaching this 16 year old and gaining his respect, but because he swung a 16 year old over, all the other 500 priests also admired the Buddha, and were greatly impressed. They all now respected the Buddha, because of how the Buddha could teach. So the Buddha won 500 of these people over to his favor, to respect him, not by showing him they had to, but by showing them who he actually was, his wisdom level.
Now back to the second question, "How can you show them friendly but firmly that they have to respect you?" No, they don't have to, but if you would like them to, that is different. If you would like them to show you respect then you have to show them qualities which they will respect. That is the difference here. You can't force people in a firm way that they have to respect you, but you can possibly show them good qualities and they will respect you. Even if you show people that you are loving, kind and gentle and everything, even wise, it doesn't necessarily mean that they will still respect you. There were still plenty of people who hated the Buddha. His cousin hated him, he tried to kill him 2 or 3 times. Even though the Buddha could impress upon his cousin and other people that the Buddha was a good, kind, wise person, it still did not help those people to respect him. So even if you have good qualities, you can never force other people to respect you.
Now, the first part of the question, "How can we deal better with difficult people, and in particular with colleagues, workmates or relatives?" These are two different worlds, right? Our friends and our relatives we have to deal with in a different way often to our workmates. Sometimes with the workmates, especially if we are the boss, yes, we can say to them certain things, "You must respect what I am doing, you must behave yourself, and so on," I think you understand that, but if you are the boss and you actually want them to respect you because of your qualities, then you still have to do what I just mentioned before.
Often it works a lot better if you are the boss and the people who work under you actually like you. I'm sure you all know that, when you have worked underneath other people, if you like your boss, you work better. You are happier, it is a better environment. Same thing the other way, if you are the boss and the other people under you don't like you, it is very difficult to get things done.
With your relatives and friends, sometimes we have to put up with them, because they are our relatives and friends. It is as simple as that, but you can be careful with how long you stay around them. If you stay around your relatives too long and it is an uncomfortable time, then you might get sucked into their aversions, their defilements and so on. But if you limit the time you are with them, then you might actually have a more pleasant time in a short stay and not get too carried away with their problems. So with your difficult relatives and friends, you may not be able to avoid them, you may not be able to encourage them to even like you or respect you, but you may simply have to limit the time you are around them.