Personnel: The success of any company depends on their ability to recruit, train and retain quality employees. The amount of emphasis in your plan for this section will depend on the number and type of employees required.
Studying your market will give you insight as to how you can make your business more appealing to people. Market research is more than just noticing trends in your customers' buying habits; it's discovering what motivates your customer to buy. Don't assume that you already know because you've been in this business for years. This study often unearths characteristics about your market that are hidden or new. It's best to discover these things before your competition.
If an online business, you need to go into detail how you will attract customers to your website. General statements like "I will use Face Book ads and email marketing" will contribute almost nothing to helping your cause unless you have detailed statistical analysis of tests you have conducted or of another similar business you have been associated with. If you do not have any data upon which you reference your estimates, it could show lack of proper thought to the remainder of your business plan.
When you sit down to compile all of the elements of your business plan, make sure you have each section able to stand on its own merits. This means you should not reference other sections sending the reader (your potential investor) back and forth between sections.