1) Monetization - Know your audience! My typical audience is 85% mobile and I monetize with Adsense. As mentioned earlier in this thread, people are much less likely to buy a product or fill out an offer from mobile than they are to click a link. The single most important change I made was switching my mobile optimized site to a non-mobile optimized site. This sounds backwards, right? Well, the day I did this, my CTR increased from 3% to 15%. I was absolutely amazed, as I had never seen a CTR this high on any of my sites. The only reason I can think of for a significant increase is the way in which 300x250 Adsense ads are presented on a mobile device. The ads literally look like a call-to-action when displayed on mobile.
2) Niche - I started in arts/crafts and made $10/day using the same method that I use today to achieve $300/day. Why the massive increase in earnings? I switch to the beauty niche and saw instant increases in likes/repins/traffic. Not only is this niche drive more traffic, it also brings many of the dumb blonde chicks that would not recognize that an ad is in fact actually an ad and not a standard link to more info.
Great discussion, lots of useful info here, lets keep it going.