What is the best way to follow up on a proposal without being annoying?

[Btaliat]

There is a need for the freelancer to know how to follow up effectively their proposals without sounding like pests. You don't need to be bombarding your clients with too many proposals. You can as well make sure that you are adding some valuable information and contents to your articles anytime you want to send additional and follow-up emails. This will make them realize that you are a professional. What other methods can you suggest?