The resource at https://sites.google.com/site/webmasterhelpforum/en/faq-internationalisation#q20 clarifies that if you implement hreflang on your site then you shouldn't implement canonicals tags as well in the same code.

Always make sure you reference the page your code is placed on as well in your hreflang set up as this is sometimes missed by people.

Yoast's plugin in WP is great for in-page hreflang coding implementation. If you are using non WP though then you may want to consider a hreflang .xml sitemap instead. There are not many tools that auto generate an .xml version though. The only one I've found is at https://www.xml-sitemaps.com/standalone-google-sitemap-generator.html. Although Screaming frog told me yesterday that it's on their development roadmap to be integrated into their software, which should be very helpful.

If you are entering into the Chinese market I would also recommend you check out http://www.dragonmetrics.com/ which is very good for monitoring organic performance of your site and helping with keyword research, you can get a free 30 day trial without entering any financial details such as a credit card, so worth setting up once your site is either more established or if you are going through the content optimisation process for the new site.