how do i implement serp features properly?

You can't really implement a SERP feature, you make the page eligible and Google decides. Which feature are you after? Featured snippet: answer the question directly in 40-60 words right under a heading that matches it. FAQ and how-to rich results were cut way back by Google, so don't expect those to show anymore. Review stars, product info, etc. need the right schema and you can test it in the rich results test. Last month and no difference is normal, it can take a few crawls.