What you have to decide, and what is handled
Simplified and Traditional are two languages, not one setting
Simplified Chinese is read in mainland China and Singapore; Traditional Chinese in Taiwan, Hong Kong and Macau. They are separate targets on your plan, with separate URLs. Choosing one when your customers are in both markets is the most common and most expensive mistake made on this decision.
Chinese copy is much shorter
The same sentence usually takes far fewer characters than in English. Headings collapse, buttons look empty, and layouts tuned to English text lengths go loose rather than break. Worth one pass through your own components after you switch it on.
The regional search engines are sent to the right page
Region-locked crawlers — Baidu and Sogou among them — serve a single language market, so when one requests a page with no language in the URL it is redirected to your Chinese URL instead of being left on the source-language page. That is a routing guarantee, not an indexing guarantee: getting into those indexes still involves their own webmaster tools.
Brand and product names need pinning
Whether a name stays in Latin script or is written in Chinese characters is a brand decision. Pin the form you want in the glossary so it is identical on every page rather than being decided again on each one.
Chinese translation questions
Add one line of code to your site, or point your domain at Proxylang, and add Chinese as a target language — Simplified, Traditional, or both. Every page is translated, including meta titles, descriptions, alt text and form labels, and each variant gets its own URL on your domain. Setup takes about a minute.
Japan is a simpler market to start with, because Yahoo! Japan runs on Google’s index — see Japanese website translation .