Hi!
Well, first of all, it's complicated to get high rank in the first place, since there is more than 200 known factors that determines organic search page rankings. There are domain-related factors, on-page factors, off-page factors, site-level factors, and numerous technical SEO factors that contribute to where your website falls on Google's search engine results pages (SERPs) for the various keywords related to your industry.
Second of all, it's also important to maintain the high google page position if you already got it, because ranking algorithms constantly changing over the time.
The best advice here would be to be completely "in" your business: read articles and official Google statements, watch for competitors sites, communicate on forums and so on.