One way is to pursue a work at home career. For a single mother, this would eliminate worries about daycare, sick children, etc. It also eliminates transportation, food and wardrobe concerns for all concerned.
In the past I have worked for Cloud 10 and I enjoyed my work. There are also a number of other agencies out there to work for.
Here is a website with a number of work at home websites and ideas. For more ideas google the terms "home agent" and "home office" - the term "work at home" generally populates more scams than work at home opportunities!
Check out the web sites ratracerebellion.com and wahm.com as well. If you're fast on your mental feet, you can even try out for the kgb!
If you want to go unconventional, you can try being a phone actor or actress. Yes - a phone sex operator. It may not be for everyone, but if you want or need to make some money what would it hurt to try? I haven't done it personally, but from the research I've done apparently there are a lot of women out there making a living from it, some secretly, some openly. If it ever comes down to my child going hungry or me becoming a PSO as it is called, I would apply in a heartbeat and at least give it a shot.
If you know anything about psychic phenomena or tarot, you can also become a phone psychic. I know some really good people persons who actually make decent money doing this, but they all say it is not something you are likely to get rich on... Just google the terms "phone actress," "phone sex operator" or "phone psychic" and watch the job opportunities populate.
Just remember, you should not have to pay money to apply for a job, though some charge a nominal fee for background checks.
Happy hunting!