Complete Wikidata items. Add labels, description, etc in your language. It is easy to do and a lot of labels are missing.
Add all words of your languages to Wikidata Lexicographical data project that stores words of all languages in a multilingual structured word database under a free license.
Add words of your languages to Wiktionaries. Wiktionaries need more assistance, and they have a lot of missing entries, translations, pronunciations, etc. See WT:ELE & Wiktionary language considerations
Record pronunciations of all words with Lingua Libre.
Take photos of plants and critters around you and identify using iNaturalist website. You can upload it to commons.
Help import freely licensed iNaturalist images to Commons. These are very valuable as the species is already identified and automatic categorization happens.
Import open access scholarly articles released under free license to Wikimedia Commons, especially the most valuable ones. Make Wikisource entries for them.
