Method: Plugins (e.g. WPML, qTranslate) and DIY
Content: translation, trans-creation, new content
Audience engagement: e.g. supporting non-Latin character sets, international social media
Website structure: Single site with sub-domains, or directories, individual sites
SEO: on and off page multilingual SEO, working with Google, Yandex, Baidu and Bing
Website deployment: WordPress multisite, in country hosting, search engine geo-targeting
Ecommerce: multi-currency, multilingual, terms and conditions
Feedback to WordPress: Adaptations to default themes, e.g. international navigation