I can give you a couple of articles that you can read but that would be silly. You've gone with keyword research first which is correct in terms of SEO. If you have any competitors. See what they're doing. Try to find the best longtail keywords that will suit your business and beat their current ones. Incorporate them in your content without sounding like a robot. SEO is about being creative. Find the things that make you stand out. Don't just follow guides.
On another note. Check your website. And check it thoroughly even if you have to use paid help. Speed, mobile friendliness, URL's, the whole lot. On-site is crucial nowadays and no content or keywords will help you if there are problems with on-site.