Writing a research proposal is a required skill on occasion. I, as a postdoc, am in "a development state" (aka I do not have much experience yet) to write good research proposals, but I did learn several essential things that you should know, which I am going to share in this post.
(1) Before you write
i- Collect research proposals in the past
The more you have information, the better. For example, when you want to write proposals for job hunting, you might want to have others' research proposals in the past, which, for example, you can find it in here. For the CAREER proposal, valuable advice is found in here.
ii- Join the group or form the group
It is important to put yourself in a position where the information is accessible to you. Your friends might be a good information source, Twitter might give you a good idea, some SLACK groups might help you to find good buddies to help each other. The point is you better move on and find a place for you. Or you might wanna form a team that might help you. Professors are busy, but usually, they are kind and willing to help. If you are polite and good, they are going to be a good mentor.
iii- Learn how to write
Writing seems to be a tricky job, and many people seem to struggle. Indeed, there are a lot of books published, and many people seem to sell their golden rules to make your writing skills improved. Unfortunately, I have not found any good advice more than "there is no shortcut to be a good writer," but I found several good tips. For example, the "Karen's foolproof" is the nice logic flow. "How to write a lot" by Paul Silva provides pretty practical tips to write a lot. At least, it does not hurt that you know these tips.
This post became too long (!), so I decided to divide it into several posts.
Good luck with planning to write a good research proposal.
