I'm very new at this myself, so take this with a grain of salt...  but I think you would approach it like bartering.   Someone has a bitcoin wallet with coins in it.  You have a wallet able to receive them.  You give them a service and provide them a bitcoin address for the payment. They transfer bitcoins to that address.  After it settles out in the network, you are in control of those bitcoins.   If you want to convert them to standard currency, you use one of the exchanges like mtgox to sell them.  Have the proceeds transfered to dwolla (or liberty reserve or whatever you choose) and then you go from there.   Or, use the bitcoins you received for your work to purchase another item or service from someone else.

As far as advertising, you could try forums or classifieds.. try googling bitcoin classifieds.