The answer to your question varies greatly on exactly what you want to do, what you CAN do, how good you can perform the services and how much money you want to make. Freelancing can be one of the most stressful things in the world, but it can also be one of the most rewarding and extremely lucrative.
You mention you have experience with affiliate marketing and web design, so, why not start off designing a spectacularly designed article type site and post a slew of articles on web design and development as well as a portfolio section with some of the sites you have designed.
Now, if you do not have any real world experience with web design (which I assume you DO otherwise you are not a designer, you are a hobbyist, lol), then I strongly suggest you get a hold of some friends and offer to build websites for them, OR, register a few domains for yourself, on various topics (subject matter) and design sites for those... Many designers make the mistake of thinking their portfolio has to be stuffed with customers' sites. Nothing could be further from the truth. If you designed it, it belongs in your portfolio. Just because it's not something someone paid you for does not take away from the fact that it's still your work and showcases what you are capable of doing.
Also, the main purpose of writing up some articles for the site is to let your intended audience know that you really do know what you're doing and what you're talking about. Your articles could be useful tips and tricks, case studies of previous clients and what hiring YOU did for them as well as any general information that could be useful to website owners passing by your site.
Your original question (the title of this thread) asked "how can I make money freelancing?" and the answer to that is partly what I have mentioned above as well as doing everything you can to actually get your name out there in front of the masses...
Get yourself a domain and design a website for yourself. Incorporate as many of the skills you have as possible. If you're great at SEO, make sure your site is on the first page of most SE's. If your greatest skill sets lie in the way of graphic design, make sure the images on your site make it POP. If your skill set is primarily "writing great content", make certain your page content is well written, proof-read and informative as well as MAKES your visitors want to hire you NOW.
Once you've got a site that you are proud of, get out there and hit the pavement. Get yourself social media accounts and befriend as many people as you can. Setup a fiverr account and be willing to do some miniscule jobs for just $5 to get your name out there. Get yourself setup as a freelancer on sites like odesk.com, freelancer.com, etc... Don't be afraid to sell your services at high discounts as you HAVE TO build a name for yourself first and doing so, sometimes, requires you to sell your time for much less than what it is really worth.
AND, if anyone says "don't ever sell yourself for less than what you're worth", they're right, HOWEVER, selling your services at low ball prices NOW is just good business sense as it helps you prove yourself to others who otherwise would never give you the time of day.
Think of it like a business lunch. A friend of mine, who is a high end attorney in my neck of the woods, always tells others that his time is worth $1,000 per hour and he NEVER strays away from that.
Now, yes, he is good enough to command that type of money for his time, however, when he tries to schmooze over new clients, he takes THEM to lunch, HE PAYS for the meal (and any "entertainment" that comes with it, if you know what I mean) and HE doesn't charge the "hope to be client" $2k - $3k for that 2-3 hour meal.
So, in reality, he just GAVE HIS TIME AWAY and HE ACTUALLY PAID FOR IT!
So, again, don't let anyone tell you that you should NOT sell yourself for less than your true worth, when just starting out. Sometimes, you just have to pay the cost of admission to be able to further enjoy the benefits of the ride, you know.