I started some pop sweeps campaign on Monday for three different countries. With those campaigns, I'm targeting users during peak times within those countries. Based on past data, I used targeting options OS - Browser as that proved to be the most profitable for me as well as the best lander/offer. So my campaigns are currently countries - best converting browser - best peak times. I'm letting this data accumulate for a week before I expand targeting.

Here are some of the issues that I'm currently facing.
- Free Time
What do I do with my free time, I want to make sure I'm using my free time efficiently.
Here are some ideas:
- Spying
1) Taking the most seen landers from Adplexity and taking the top publishers websites to track trends of which publishers are a good source of traffic.

2) Contacting those placements that are profitable to me so I can run traffic to their websites instead of running through popads. How do you accomplish this? Do you contact the emails from the WHOIS directory? When contacting those emails, are you drafting a email in way that it doesn't hit their spambox?

- Landing Page Variations
1) Create more landing page variations to squeeze more ROI.
- Traffic Volume
1) Since I'm running these campaigns for a whole week, my goal is to take all the profitable placements and start targeting all browsers. The issue here is there isn't enough conversions to whitelist placements. With that being said, I'll have to run these campaigns much longer to get enough statistical significance.

Simon these are all great ideas. If I were you though, I would scale that NL camp to a few other sources right now, since it's already profitable on this source. Maybe start with all the biggest sources (ZP, Propeller, Popcash if you don't need carrier targeting, Adcash...).
Systematically testing multiple geos for a single vertical is a great way to scale! Best of luck with that. 
Amy
[EDIT: Just noticed you're sticking to european geos. Why is that? Asian/African/LATAM geos have cheaper traffic that convert better in general.]
Scale your camp as long as it is alive.
Each day 2 new pop sources.
Hit 10 of them, 2-3 will work if you're lucky.
Find a way to make your camp targeting wider. Targeting OS-Browser is an revenue killer in absolute terms.
Always put absolute numbers over ROI.
On contacting publishers:
1) Look for the names behind the site. Look for copyright notices, authorship notices, etc.
2) Find out if they have a social media presence. Twitter, FB, LinkedIn etc.
3) Throw them a BRIEF contact via those social media channels. Key is BRIEF. (Obviously Twitter enforces that).
You'll have a significantly higher hit rate than via contact forms that way.
Obviously, if you can find a phone number (and it's one that they want to be contacted on - don't scrape personal numbers from Facebook or something
), use that in preference to all other forms of communication. Again, brief and professional.
Finally, when contacting, make it clear that you're not an SEO buyer, and that you'd ideally like to buy in significant volume. Obviously tricky to fit into a brief email, but generally publishers get a lot less enquiries along the lines of "I'd like to buy all your ad inventory" than they do "I'd like to pay you peanuts to insert a paid article onto your site and hope you're not clueful enough to notice the do-follow links" 
First of all, you are doing a great job and congrats on getting 2 out of 3 countries already in the green!
I would focus on scaling your campaign instead of going direct to these pubs.
Why?
1. Time. You are a one man army which means you are limited by time. Its way more profitable to invest your time in scaling your numbers while you are in the green than on negotiating with 10 pubs who now give you a combined profit of less than 50$ a day. Try working on making that 500$ a day using popads. Invest your time in banner/lander optimization, scaling and testing out other pop networks such as adcash, propeller, wwwpromoter, etc.
2. Economies of Scale. Popads probably gets better prices than you would get in direct cooperation with these sites because they buy a big chunk (if not all) of the volume of these sites and then sub-sell it to people like yourself via their platform