Invest time BEFORE you start writing a grant application to make sure you meet ALL of the eligibility criteria.
Applicant criteria and project/program criteria are different, so check both sections of a funding body's guidelines before starting your application.
Common things to check for are:
You have the right organisational status
Your project/program meets their priorities for that round (these can change from one round to the next)
You are based in the right geographic area
Whether partners are required or optional
That you can deliver the project/program in the required time
If there is a co-contribution required (either cash or in-kind)
That you can manage the grant funds you're applying for.
On top of that, if a funding body says they want to fund innovative approaches to a particular issue, make sure you draw on the innovative aspects of your project. Your aim should be to make your project line up directly with the funding body’s aims for that particular grant round.
Give funding bodies insight into a project they would love to fund.