Here are a few things that you can do for ensuring that there is no organic traffic loss while migrating your website to a new hosting provider:
* Check the organic traffic and keyword rankings and keep a record of it.
* Crawl your old website and record all the URLs. Use an online tool like DeepCrawl to check the changes in the website before and after migration.
* Check the loading speed of some key web pages (e.g. homepage, main category, sub category, product page, blog post). You can use Pingdom Website Speed Test.
* As far as possible make sure that the URLs of your migrated website is the same as the old ones, don't make any changes in the URLs.
* In case you are changing the URLs as well, you need to set a 301 redirect that points to the new version of the URLs.