This FAQ is meant to answer many of the questions I see, both directed at myself and the community in general. Please don't take my answers as gospel, they are merely how I see things and won't necessarily be right for you. In fact, if you agree with everything here, you might want to get yourself checked out.
How Much Can I Earn?
Seriously? C'mon. As much as you're willing to work. There are at least 2 writers making over $1000/month, a handfull over $500/month, and an enormous number over $100/month. InfoBarrel isn't some get rich quick scheme, but everybody who sticks with it has been successful. Everybody.
An extra $100/month is significant, and you can grow your earnings far beyond that point. If you haven't signed up, you should do so now. This FAQ isn't going anywhere.
What's Better, Quantity or Quality?
Both, but if you are only looking short-term it appears to be quantity in my case. There's no way to know for sure until I do it, but I bet having 2500 articles that earn is best (most quickly) done by doing each part of the process separately:
1. Keyword research (complete)
2a. Article Writing (675/2500)
2b. Article Publishing (595/2500)
3. Article Promoting (backlinking & rewriting & interlinking) (~250/2500)
Why is this the case? Patching makes any process more efficient, I'm just taking it to a much larger scale. Additionally, I am going to have excellent metrics for each article before I promote it, so there will be an minimal amount of wasted energy through this process. (not everything needs 100 backlinks)
In general, quality trumps quantity, and this holds true for article writing.
How do you choose topics?
I will write an article about any topic where I believe the same information will be relevant 5 or 10 years from now. I want the effort I put in them to be sustainable for as long as possible, even if the yield slightly lower. Writing about anything new: new technology, new cars, new movies will most likely experience a drop off in traffic at some point, and then you're starting over. Oval mirrors will always be oval mirrors, and I don't want article writing to be a full-time job for the rest of my life.
How much [metric] should I look for?
Sorry, but there's no answer to these questions. It will always depend upon how much time you want to spend promoting, your SEO skills, changes in Google's algorithm, advertisers spending money, and how much work you want to do. Choose how you want to spend your time, then create a strategy that will work based on this. I don't want to promote (at least initially), so I go for lower competition, and a likewise lower traffic and CPC on average.
How long should my articles be?
For Adsense, you are probably looking at a minimum of 500 words in order to activate the skyscraper ads that will appear on the left-hand side of the page.
For Amazon, you probably want shorter articles (~400 words) so your Amazon links are more prominent. Though you can also do longer review articles that work well.
The debate will rage on, but I think it comes down to what your best ROI is. If you have no problem writing a 1000 word article, you have many more opportunities to use long tail keywords, keep a user on the page, and "cash in" on your work. I fall into the 700 word range most of the time. Remember, it's not about what's "right", but what's right for you.
I've published [x] articles. When will I start earning?
You have to develop an understanding of article marketing. If you're coming in without an understanding of keyword research, SEO, and promotion methods, your first articles will serve as your schooling.
It took me around 50 articles to get any results. Give yourself that much time at a bare minimum. I also studied for hours every day in order to learn how to do this. If you only have 1h every night, it might take 100 articles until you "get it." (Also, don't let a lack of SEO knowledge keep you from writing!)
But [person y] is earning and they only have [x-10] articles!
There are usually two explanations for this. One, the person has some prior knowledge of how the Internet works and are thus farther ahead in the learning process. Two, the person has some specific and valuable knowledge to share, such as stock analysis. Remember, even though it might appear they're getting "faster" results, they had to take the time to acquire that knowledge at some point. You just don't have access to that part of their timeline.
More will be added if/when I think of something else important to say! Feel free to leave a question or comment, or mention anything I ommitted. Oh yeah, and sign up if you haven't already!