humidifiers are cheap. $10 craigslist. $20+ new. My rh is 15-20%. in my basement of 800 sq feet, temp upstairs at 74, a 250sq ft $10 humidifier raises the rh 10%. Lowering temp 4 degrees in house raised it another 10%.
-Don't use clothes dryer. Hang wet laundry.
-shower with door open, no vent
-bowl of water over vent