How to convince Grant Reviewers?
Reviewers are scientists working after hours. They usually do not get paid for their work. To convince a reviewer, you need to show that you appreciate his efforts and don't waste his time. Most reviewers are from a related field, so you can assume they speak the same language but do not know most of the components you are working on. Generally, reviewers can be convinced by making their work easier. Reviewers typically have to comment on a number of criteria. Show them the value of your work by providing clear answers for each criterion in your application. Commonly, these criteria include:
Feasible
The methods are known, you have the equipment, preliminary data, papers
Adequate
The right call and the right time
Original
A new combination of skills, a problem you solve, a unique context
Risks covered
Preliminary data, risk analysis or contingency plan, plan B
Productivity
Your CV, complementary collaborators, papers
Competent
Match of researcher and project (why are you the best person to do it)
Most grant agencies publish the criteria for review online. Generally it helps reviewers if you provide explicit answers to each of the criteria. Ideally in bold letters. Afterwards, provide the details to add scientific depth. Your reviewers will be happy if they won't have to search in your application for the things they need. Having happy reviewers is a good step towards a successful application.