Remind them why they need you. Your proposal should immediately remind the prospect of what their problem is and why they are talking to you in the first place. In other words, you should immediately start your proposal off with the pain your prospect is feeling. Are they not making enough sales? Is their message not getting out to their audience? Could their life_savings be in jeopardy? They are talking to you for a reason.
Now you may be thinking: Uh_oh, I've written business letters, but I've never written a business proposal. Don't fret! Proposal writing is simpler than you think. Basically, you need to introduce yourself, explain what you're proposing and why, describe any costs involved, and convince that boss or prospective client that you can be trusted to fulfill the promises you make. You can find lots of advice on the Internet and in special proposal writing packages like Proposal Kit. Starting with a proposal product like this can speed up the process by giving you pre_designed templates and lots of samples you can learn from to create your own winning proposal.