Getting approval for new trails is a difficult yet rewarding endeavor. It's generally a lengthy process that involves a lot of hard work and patience.
First, there's the question of ownership. Before you set a foot on the property - let alone begin working on it - you must determine who owns or manages the land.
Establishing a personal, working relationship with that landowner or manager is essential. Having a complete vision and plan for your trail project is also important: Rough ideas and suggestions are rarely enough to secure a go-ahead.
If your plan involves building and maintaining a new trail system, it's important that your project is tied to a local, established bicycle club or other respected volunteer organization. Being able to demonstrate that your project can draw on an abundant labor pool for construction and on-going maintenance is a plus. If the work seems as if it's going to fall on the shoulders of one or two individuals, the credibility of the project will suffer and approval may never come.
The more you know about a proposed trail site the better. Hike the area as many times as possible before placing that first surveying flag. The more familiar you are with a piece of land the better you'll be able to fully utilize natural features to make the trail interesting and aesthetically pleasing.
These first two steps - securing permission to develop trails and learning the lay of the land - can be time-consuming. But they're a crucial investment that will pay off with a trail that is more enjoyable and durable.
You might also consider getting professionals involved in your trail design, construction and maintenance, such as the Subaru/IMBA Trail Care Crews.