In proposal writing, your first step should always be to gather information about the party who will judge your proposal. That's because you want to present a proposal tailored to that party's specific needs and knowledge level. In other words, you need to put yourself in the other party's shoes and look at the situation from that party's point of view. If you are pitching to your boss or your company executives, you might already understand their positions and their concerns. But if you are pitching to people at another company, then you will need to do a bit of work researching who they are, what they do, and what their needs are. Yes, that research can take a bit of effort, but putting in that effort makes your proposal much more likely to succeed.
In the business world many companies ask more than one supplier to submit a proposal showing what they might charge for a particular product or service. If you are new to the supply side of this situation you may need to refer to a sample proposal template to make sure that the bid you plan to submit is in the correct format. In many cases if a proposal is not formatted properly the company who has requested the bid will not even bother to look at it.