I read on the spanish blog
Asà no son las cosas a recopilation of
ten tips to do true journalism. They're all also useful for infographics, as infographics are journalistic pieces. The tips on bold, comments made be myself.
1. To have the best sources is and always will be the keyOn graphics, which usually are more explanations than news, those sources are the data and the documentation. A graphic with good data and good information has more than half of the way walked.
2. You must know you'll be copied in 10 minutes time: offer more and more, step by stepInfographics are also that. A way to give context, some little data worth a spread.

This grahics about the Txalupa (a basque ship) by Fernando G. Baptista has the usual impressive illustrations, but the little details give the graphic a great one.
3. Write a blog, talk in Twitter, make photos, but, above all, show what you read, who you areWell, this point may be difficult to export to specific graphics, it's essential for online communication, but just on general journalism.
4. Your readers don't want just you to tell them things, they look for recommendations also: link and commentThis is the reason why indicating the sources is very important. Also little pieces on where to find more information about the topic. It adds value to the graphic.
5. Make mistakes, learn to rectifyAs anywhere in life...
6. Don't wait, searchInfographics departments must be proactive. You can't stay seated on your place waiting for the other sections to give you what you have to do on the day. Infographics departments must offer topics and graphics to the other departments. Propose, think, go where the information happens... Work as any other department, not as a service. This maybe one of the most important tips.
7. Seize the work of others, tell it's not yours and use itIf you make clear where you take the information from, is good to seize it and offer it. Meanwhile you tell the truth, is good to give your reader the best you can.

TRANSLATION: Data obtained from a graphic by The New York Times ellaborated with data from NASA.
8. The automatic works, but a good editor always gives a lot to the informationYou must not be a mere translator of data into charts or any kind of graphics. Always try to add value to the information, to go a step further, to turn data into information.
9. If you don't have exclusive information, edit: photos, context... everything that would make a better readingIf you know everybody is going to have the same information the next day yu must go a step further. Try original ways of explain things. As somebody I don't remember used to say: The important is not the one who publish the information, the important is the one that gives the information on the good way.
10. Can yu go to the street with good equipment? Go. You can't? make good web researchingInfographics department can't be attached to the chair. They must go to the streets also, where information is, where news happen. If you can't for any reason, it's not enough just to google. Search the web as the journalist you must be, not as a common user. And use the phone also.
11. Don't just attend to press conferences, the interesting things are always outsideThe press conferences of infographics are the press releases: informs with a lot of graphics already done. It's not enough for a good graphic, it's just the first step. Go further, go further, go further.
12. Friends are there to help you, seize them but compensate themOk, the translation of this tip for graphics could be this: You have a friend who is a doctor? Send him the graphic of the lung cancer you're doing to check that everything's allright. Maybe you're graphic is a little complicated? Show it to your mom (the best and fiercest critic you can have) or just someone who doesn't know anything about the topic.
13. Never lie or exaggerate if it's not necessary: let the reality spoil a good headlineI think you never need to lie. Keep the real scales on charts. If someone catches us lying they won't never trust us.
14. There are thousands as you. Which is your difference? Use itIs the basis of all what we've told before.