I'm happy freelancing ~10hrs a week and earning about the UK's average wage. Three days a week at a company would be perfect.
I started with some of the freelancing sites. It's hard to find decent work, but if you do it with an eye on building relationships it can be worthwhile. (pro-tip, put some money through the site and hire yourself; takes about a week to do without arousing suspicion, but then you have ∞ly more chance of geting hired [$50-100 dollars should be fine])
Business forums for accountants, truckers or anything, can also provide you with leads. Just make sure that you show an interest in their work, not just in getting work from them.
Next, find a way to help the people that you've built relationships with make money. Adwords, I didn't know much about it, but a few hrs later and I had turned a 50€ a day campaign from loosing ~1/2 the π (profit) to doubling every day. (email me for some of the tricks)
Google apps script is just js and easy to learn. With a small number of regexen etc and the simple APIs into google's services GAS gives you, I have been able to speed up ~5-10 jobs that were done daily, from taking ~3hrs, to the time it takes to click a button. Apps that would take a week or two elsewhere are 10hr/day jobs with GAS.
This took about 6 months, but I have been working for about 1yr now at ~10hrs a week and I just ensure that people realise that 10hrs is my schedule and not to ask for more. I'm sure the _value_ I have provided to these businesses would allow me to double my rate tomorrow and face zero resistance; from ~£80k p.a pro rata, and I would say I am a moderate programmer at best.