You can help:

• By adding the relevant categories to the bottom of each page. Keep to the key relevant categories. 2 or 3 categories are often enough; some pages may have as many as 6.
• Where you can't work out which categories to add, add {{catneeded}} to the bottom of pages without categories.
• If you have tech skills, run the Pywikipediabot (it's not that hard, but takes a little while to get familiar - you could be doing basic commands within an hour. Contact Chriswaterguy for help.) Use an "Add category" command - this finds pages which refer to a certain topic, checks if they are in the relevant category, and if not it prompts you to confirm adding the page to the category. A typical command might be:
• python replaceedit.py -regex "(?si)\b((?:water?|Wastewater?))\b(.*\$)" "\\1\\2\n" -excepttext:"\[\[Category:\s*Solar cooking" -excepttext:"(?si)(\#redirect\s*\[\[)" -namespace:0 -namespace:102 -summary:"adding based on search match and manual check." -log -xml:currentdump.xml
• You can press the option b for [b]rowse to check a page before confirming the edit. This bot is still being tweaked - contact Chriswaterguy for the latest info.