[KarlJones]

Well.  Sometimes saying "I am a single parent" feels OK, for instance if you are testing out an idea and want to know if it will present other problems (not being able to work sometimes). Or if you want feedback from other single parents. 

Other times it feels like your holding out a cap infront of you and that really does not feel nice.

The only real selling points I can see that matter are...
Are you a crook?
Are you reliable?
Are you any good?

This is called Asymetric information, you know the answers, they do not.  So you have to find solutions to them.
The best way to solve all three, from what I can work out, is to try and look as professional as possible.  Think like a thief for a bit. 

What does he look like? 
Does he have references? 
What is his stationary like? 
Would you trust this man to let himself into your backgarden while you were out?
Do you even want him on your doorstep a second longer?
Can he even clean himself let alone the windows and frames?
Is he just going to rip me off?

People do have folks like this knock their door and ask for work.   They do not get work because they never get round the asymetric information problem.  They think what they say is more important than how they present themselves.  Yet they are saying exactly the same thing as a person who...

Looks profesional.
Has references.
Has business cards, nice flyers and a website.
Has insurance.
Just wants to talk about what he does.
Is clean and presentable.
Offers some sort of guarantee.

My selling point, to be honest, is the fact I happen to know what stops them from having a window cleaner.  Beat the asymetric information problem and you have solved the only thing standing between you and a customers money.  Everything else just distracts them from the fact you just want to sell them a service.

[Templar]

I suppose I'd better apologise, I was a bit sharp but you do need a thick skin, and you do need to set small milestones in between the big ones.