I’m going to give you an honest opinion which may sound harsh but I’m really not. No. You are not ready to charge. You should be focusing on producing consistent images. You have a lot of poor angles (shooting down on a child), clipped fingers and feet (look up guidelines on where to crop limbs), soft images and images that lack/ or need a better depth of field. You have images that could’ve benefited from fill flash. You need to calibrate your desktop monitor and find your post processing style. All of this takes time and thousands of shutter actuations. Incorporate flash into your workflow now so it becomes second nature. There are too many “natural light” fauxtographers who shoot at f/1.8 who are too scared to learn flash and when it’s needed. Do you know it’s harder to raise your prices once you start out as a $50 Facebook photographer? Master the skills and start out much higher. Have a business plan, DBA, tax attorney, license, etc. You’ll soon realize that your cost of doing business exceeds $50 a session.
A D3100 is a good beginner camera and that’s about it. It lacks in good high ISO to low light, has a small sensor with poor image quality. A D7000 is the minimum body for professionals (just my opinion only). Of course, you need fast glass with a fixed aperture as well.
The good: you have potential, much more potential than the so-called pro’s advertising on FB. Your candid shots are pretty good, too. But it’s one thing to photograph candid and family moments then when you are hired to perform and produce a quality product.
Just my $.02. Of course, you can tell me to stick it up my wazoo and go out and do your thing. But you asked….and I replied. 🙂
P.S. for quick learning tutorials, check out the AdoramaTV channel on YouTube as they have videos for beginner to advanced. Also, there is a widely accepted web article on the www called “Benji’s Rules of Good Portraiture”. Google that.