Darren,
The only site I needed when I filed my K1 was visajourney.com, you'll find all the examples, flowcharts, and sample forms you'll need, along w/extensive forums to answer any questions you might have.
There are obsessive people who will argue about whether cover letters will make their application extra special and within that group you'll find sub-groups who argue about what the content of the cover letter should be, and within that sub-group there are offshoot groups who argue about what order the content in the cover letter should be presented. There are similar arguments about whether to use binders, three-ring hole punchers, etc.
If you're new to this, you read these debates and can't help but think it's all frightfully important. It's not. It's just a form of mental masturbation by nervous people who'd like to feel they have a bit more control over a process whose outcome will have a huge effect on their lives.
Bottom line, if you don't want to hire a lawyer: read the instructions again and again, and make sure you've filled out your forms correctly and clearly. Put everything aside for a few days, and re-read the instructions and go over your answers and review all the evidence you are sending along with your package. Repeat again the morning you're planning to mail everything. If everything is in order you're good to go.