Executive Summary should contain a gist of all the points mentioned below.
Overview of business should contain info like its type, on-paper stuff, location.
Clearly mention the kind of products of services your business will offer. If multiple, categorize them as per their domains or prospective clients.
Market analysis should highlight on how and where your business play a role and why customers will go for it. While doing this activity you will get acknowledged with what all similar or linked products or business already exists in current market (even those which you may not have heard till now but do manage to survive!)
In sales section include your marketing strategy. You can also specify whether you’ll go for paid advertisements or rely on mouth publicity.
Risk assessment needs to contain what all are the possible threats to your business and actions to mitigate them.
Funding is a very crucial part of any business. You should have estimate of money required to have all the resources required for your business. And as always here also goes the rule of thumb, actual costing always goes to the higher end of the estimate! Finance part of your business plan should also what is expected revenue in coming few years.