I've given myself a raise in my freelance writing business. I'm the one with the corner office (quite literally) so it's up to me to give it to myself. To grow and be happy I need to like my job and have enough money to live. What I'm now doing to try to raise my writing rates is this:
Negotiate periodic increases. When I negotiate a new contract with a client I'm now telling them up front that every six months I review pricing with clients and they are subject to increases. This way, I'm not locked in to the same prices forever and when I'm ready to raise rates, they are already using me and seeing what value add I bring to their business.
I have a client I've been dealing with for a long time and they pay me a bulk rate but I wish I'd thought of this when I negotiated the contract. Lesson learned.
Quote higher on new client quote requests. New clients are finding me through search engines and through word of mouth. As long as they're finding me, I have nothing to lose when I quote them.
How else can I raise my rates unless I choose to raise them when I quote? I figure if I'm busy enough I can afford to quote higher than I usually do when something falls in my lap. If I don't win the order, nothing lost. I know a lot of writers (that I'm just as good as) will charge more than I do and I want to improve my status as I go on just as I did in the business world.
I am not about to rob clients blind but I deserve a cost of living increase yearly as I develop my knowledge and skills and prove my worth and the only way I'll get it is if I decide to pursue it. Besides, if I quote high and they want to negotiate (and I really want the gig) I'll have wiggle room.
Find more streams of income. I have a blog post that's been earning me monthly income for 2 years despite taking only 5 minutes to write. I'm going to find more of those so I more have passive income and can be choosier about writing assignments and gigs I accept.
A huge part of self-improvement is avoiding complacency. If you want to make $100 an hour and you're only at $15, only you can command that extra $85. When you get to $100, don't settle. Stretch your legs and strive for $200.