Subject: growing colonies of bacteria

I am doing a project for my chemistry class measuring the effectiveness of 
different mouthwashes in killing bacteria.  My procedure is to collect saliva 
and mix it in a 1:1 ratio with a mouthwash and then put a drop of it on a 
plate.  I would love to be able to grow colonies so that I could count them, 
however, so far I have only been able to grow lawns, not distinguishable 
colonies.  Is there a process by which I have a better chance of growing 
colonies?  Thanks!

Re: growing colonies of bacteria