There are many resources to develop a proper and comprehensive marketing
plan, if you don't wish to hire a consultant to help.
From the library to book stores but if you're looking for funding from a
financial institution, by far your best bet would be to ask that financial
insitution for a marketing plan (business plan) template. They all have them
and using their versions will only increase your chances with them. Even if
that's not the purpose of you wanting to build a plan, ask any major bank for
the template and they'd likely be happy to oblige.
Good luck!!
