Freelance Side Jobs: Am I in Over My Head?

My basic personal finance rule is that if I'm going to splurge on something, I need to earn at least that amount in freelance income over the year. My base salary ($60k) pays for my rent, food, bills, and savings. Anything on top of that should be earned separately.

While I put 45-50 hours into my full time job each week, there's always extra time when I'm sitting around thinking I could be earning more money.

Freelance writing work has always been a great side project for me that pays fairly well, but I need to be careful not to sign myself up for too many extra gigs. It's easy to do that -- as the potential to earn extra income and increase my pleasure spending per year is great.

I currently write for a blog and earn $25 / post; each post takes me about 30 minutes to write. I can write up to 20 posts or $500 worth per month. I've been on and off with it for the past year, but I've been trying to hit the 20 post limit each month now by writing in the early mornings before work.

Last week I replied to an ad online for a blogger and found out this blogging job was more like writing long feature articles than quick blogging. They take me a lot longer to write than the short ones for the other gig, and require more research, so I'm charging more for them. At first I thought it was just a few blog posts they wanted, or maybe a couple a week ongoing, but it turned out the CEO liked my writing and background and wanted to meet me and discuss an ongoing writing gig including some tech writing, article writing, and press releases. He knows I have a full-time job that is my priority during the day, but if I can do some extra side work on the weekends, then I'll do it, and do it well.

It's just that I don't want to spend every waking moment of my life working. It's not that bad because I enjoy researching technology news and writing about it, and I hated doing that full time, so it's fun as a hobby almost to do it on the side. Yet I want to make sure that the quality of work I do meets my personal high standards. And that means my life becomes devoted to work.

On top of that, I'm taking these classes and just extremely busy. I like being busy, and I like making money, but where do I draw the line? How much free time do I really need each week? I'm so often bored on the weekends, I'd rather be earning extra income than being bored and probably going out and spending money.

If you earn freelance income on the side, where do you draw the line? How much extra work is too much?