When I started out I advertsied everywhere, doctors surgeries, church halls, went round tha local business park and left leaflets/advert for the staff room. Also I go to lots of toddler groups and leave my cards by where the parents sign in. I tell everyone I speak to that I am a CM and give them a card even if they don't have children they might know someone who does.
I put adverts through hundreds of doors which I did myself and probably lots went through irelavent letterboxes but am sure some must have got through.
Also put adverts in local shops. If your local schools don't do wraparound care then go and speak to them and make sure they have details to give to parents that ask. Our local CIS works with schools and supports us lots with this so it might be worht asking them as well.
GOod luck and I am sure you will be working soon. I too had to get some part time work before my childminding took off, I was doing Betterware and also got some creche work which I got childminding work from