If you are looking for the expert advice, let me tell you what I do in my Wikipedia page articles to eliminate grammatical errors. The thing that matters the most is the proofreading and editing of the content. For this purpose, you can use online grammatical errors sites like Grammarly. It will help you in eliminating the grammatical errors from your content. I learned this from several Wikipedia editors for hire which I found on https://wikicontributors.net/. They practice this diligently.