Templates are a major time_saver: The most obvious benefit of using a template is that it's a major time_saver. You don't have to create everything from scratch because a lot of the complex work is done fore you. A template allows you to drop in the look you want and then customise according to your needs. This is significantly faster than starting from a blank canvas. Templates can give you a competitive advantage: When you manage projects and delivery it successfully, it's essentially competing with other project managers, departments or against another company.
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.