The Details are important _ Pay special attention to the details. They affect your readers very much. Details like alignment of the texts and the number of lines which your paragraphs include, can make readers bored or can interest them.
Then, deliver your polished proposal. Save it in a PDF file or print it out, or both. The best delivery method for you depends on your relationship with the party who will receive your proposal. It's common to attach PDF files to email these days, but for your situation, it might be most impressive to hand_deliver a nicely printed and signed proposal.