I'm going to do this in English because those who have asked about this have all been English speakers. Most of the tips are about two things: trust and patience. So if you don't feel like reading them all just get some trust and patience and you're all set. :) And if you don't want to know how to photograph your friends you could just look at the pictures. I took this opportunity to re-port some fave portraits. Because I can't get enough of these beautiful faces.
On permission.
1. Always ask if they're okay with you taking their picture. Always always ask if it's the first time you're photographing them. I often ask the second and third time as well. This is simple respect.
2. Always take the camera down if they protest (having given their permission another time does not count as eternal permission). Some are seriously uncomfortable with cameras - always respect this! Most only whine for a while, then change their mind, and want their photo taken after all. Still, always take the camera down. It's better to be on the safe side. This too is nothing but respect.
Also, some whine for a long while, even though you actually know that they only whine because they think they should ("oh noooo, no photos of little ugly me, I look so ugly today"). This is where it may fit to remind them that they always say that, and then they always end up stealing your photos to use as their Facebook profile picture anyways. This being said, remember that everyone has bad days and someone who let you photograph them yesterday might not feel up to it today. Respecting this is part of what will make them more comfortable in front of your camera in the long run. And trust is all about the long run.
3. Be sure to ask if you can post the photo online too. Be specific about where you're going to post it. I have stopped posting photos of other people on Facebook, so I ask for permission to post photos on my blog. Most won't mind - still, I always ask the first time I photograph someone. This is how I would like everyone to treat photos on the internet, so this is how I do it. Also, even if you have permission to post photos, if the person sees the photo and changes their mind later - take it down.
On trust.
1. Never ever ever post the bad photos. You know, the unvoluntary grimace ones that other people might think look funny, but the person in the photo will more likely get hurt about. Some are tempted to do this just for the laughs they'll collect from others; it's never worth it. Your friends need to know that all the photos you post of them will always be awesome, flattering or at least good enough.
2. Let them know that the obsessive clicking is for their own good. Most will dislike the sound of the camera and feel threatened by it ("is it over soon? Why is she taking so many?"). And I really do take an insane amount of photos, it's just clicking non stop. Tell them and tell them again that the amount of photos taken is raising the chances to get good shots. At least, that's how I work. Most people will look crazy on every other shot. :)
3. Give it time. Most are uncomfortable the first time. Stick with it. They will get used to you and your camera. Several of my friends have told me things along the lines of "I hate when other people take my picture, but it's okay when it's you". That is the best compliment I can get. I even have good friends of mine tell my new friends on parties: "This is Kristin taking your picture, you can trust her!". This is what you want. You will be known as the crazy obsessive camera person. (Joel asked me the other day in a worried tone: "Are you okay? Is there something wrong?" "Why?" "You haven't taken any photos all day!"). This, too, is what you want. People will accept the photographing more once it's obvious that it's always there - that that's just who I am.
4. Remind them again that they actually want photos of themselves looking good, and the photos will turn out better if they actually let you take them without interrupting.
5. Once they trust you, you can just ask them to do anything, they will look their true gorgeous self whatever they do. Besides talking (see below).
On how to make people look as good in photos as they do in real life.
1. Learn how to "direct" after your own taste. Again, time and patience. I didn't do this consciously, it just happened after a while that I learned what I like. Most obvious example: I often ask people to not raise their chin. Many people do this, I don't know why, but it gives a sort of almost frog perspective that's not too flattering. So chin down, eyes up. But that may be just me. Again, learn what you like.
2. Most of my "directing" is just asking people to do that thing again that they just did. (I think all my friends recognize this!) Most people will look amazing when you put the camera down or before you had the time to pick it up. You'd think that what they did is something "natural" that "can't be faked" but what I've learned is that if you can describe what you just saw, they can do it again. "Turn your head that way ... no, more to the left ... and then you had your hand there ... and then look more right". So basically, learn how to really see what they do that you want to capture, then learn to describe it accurately.
3. If you shoot several people, you'll have to take the amount of photos you would take of one person, times the number of people in the photo. That's how many it will take for people to look in the same direction at the same time with the same expression (if that's what you want). Tell them to please look in the same direction longer than they think they need to, so you have time to direct whoever's looking in another direction. So basically not just "look at me!" but "look at me and keep looking at me until I say something else!".
4. If you shoot several people and they all have this stiff family photo smile that no one will like afterwards, ask them to just look at each other and then be quick with the camera. If this is people who know and like each other they will almost always crack up with the most lovely expressions. I tried this at numerous parties and weddings. when I photographed all the guests. It never fails.
5. Also, ask them to stop talking. Very few people will look sane in a still shot while talking.
Last but not least: Always show that (or pretend like) you know exactly what you're doing. The second you start to doubt your ideas, the people in front of the camera will, too. There's nothing wrong in saying "I wonder if this will work, let's try it!" if it sounds like you mean "I think this is going to be awesome". If it sounds like you mean "you're ugly and I'm not sure how to save it", insecurity will spread.
Also, you have got to love people.
