Once you have bought your domain name you should immediately park it so you can generate a bit of revenue on the side while waiting for it to be sold. Your parked domains will automatically get related ads displayed on them. If, for example, you have a domain called TradeMortgage.com then it will get ads related to loans and mortgages.
When people visit your domain and click on the adds you will get payed. It's that simple. Don't expect to get rich by this. Most domainers only make a few bucks per month by parking.
There are tons of parking companies like smartname.com, parked.com, namedrive.com, trafficz.com, skenzo.com,... I personally use Sedo.com. It is a good place to park your newly bought domains for free.