This article was a good read and a confirmation of most of my experience thus far as a freelancer.
In point one, high value clients are basically the blessing that make or break your freelancing gig. Personally, the way I've found them has mainly been through networking. A guy I knew who knew a guy needed this, or someone who knew me recommended me for something someone else he knew needed. There are literally less than a handful of clients that I've had that weren't connected in some form like this. Mind you, as an introverted guy my networking doesn't pale in comparison to someone who actually tries to do it, but I guess that should be an encouragement to any non-extrovert freelancers out there. It is possible, however do keep in mind, you'll have to crack your shell a bit and work really hard so that your networking grows naturally.
Point two is advice that I don't think any one ever takes upon first hearing, but eventually learns and uses once they've actually dealt with one of the "low value clients". Although, even now sometimes I accidentally say "yes" to one, and regret it quite quickly.
I had a period of 5 years where I lived in Colombia, South America. Unfortunately, most clients over there seem to fall under this category, much to all my classmate's dismay. Your skill is rarely appreciated for what it's worth, almost EVERY project starts off with a "How low can you leave it for me?", etc.
Now to be fair, I've worked with many great Colombian teams before (who usually received clients outside of the country, coincidentally enough) so it's certainly not always the case. However, I've only had 1 client (Canadian) that I would say was troublesome (revision heavy) during my freelancing life, and they were probably my 2nd or 3rd so I was extremely new to the whole game.
Point three is certainly good financial advice. In my case, I fall under a VERY frugal living scenario which allows me to pocket most of my earnings, on top of being raised as someone who simply isn't used to spending much on myself (although the few times I do, such as for a laptop or other device, it normally benefits my work as well). During the middle of the year I was in one of these slow periods, but I still managed to make a small chunk of change every month (enough to squeeze by the bills if I had to) AND used the free time to improve my skills with various personal projects. It certainly helps when you got stuff backed up in the bank though.
I'll continue my thoughts of the final 3 points in a future post, but I highly recommend you read the article and heed its tips.