If you haven't already, the first step is to get your Ground School completed, you will need to have insurance in place as well. Once that is done you can start with the application. I would apply for a Simplified Site Specific SFOC for your first one, take one section at a time and complete the section before moving to the next section. The first application is a lot of work, once you get past the first one it becomes easier as you just need to complete your site plan and update any information that may have changed. Sections 2 to 4 will just be a repeat of your first application unless you have updated info. Your application should be complete as possible, don't leave anything out. Flite Lab has excellent information as well. The SFOC application comes with instructions long with Site/Plan example(See my attachment). All your measurements must be in nautical miles, not kilometers( I made that mistake on my first app) Keep in mind the whole process is under review and changing.
P.S. At some point you will need a ROC-A as well, so if you get a chance to take it with your ground school, go for it.