Here are some of the top soap-related questions people search for on google. If you make a post that specifically addresses this question (i.e. make it the title of your post) and optimize for keywords, you may get some general traction. The above poster is right about targeting your audience, however, niche generally trumps going for mass appeal.
I'll give the question that gets typed and the ballpark monthly number of searches in the USA
"how to make soap" 27,000
"What is castile soap" 8,100
"How to make foaming hand soap" 6,600
"how to make soap at home" 5,400
"When was soap invented" 4,400
"How does soap work" 3,600
"Is dove soap antibacterial" 3,600
"why does cilantro taste like soap" (this is an oddball one but fun) 2,900
"how to make antibacterial soap" 2,400
"how to make soap without lye" 1,900
"who invented soap" 1,900
"does soap expire" 1,600
Hopefully a few of this might be inspirational!