Writing a research proposal can seem a daunting task initially. I'd never had to write one before now! But I soon realised that the trick to writing a research proposal is to be as clear and concise as possible so that the reader knows exactly what you are trying to explain. I found that I could write with more coherency once I fully understood the concepts related to my proposal. This involved doing a lot of additional reading of primary literature and thoroughly digesting my project supervisor's publications.
If you are reading this before starting your own proposal...good luck! You can do this!