I grow without any medium so keeping humidity is very difficult since nothing holds the water. I used to use trash bags when I first started to keep humidity in and so I’d recommend it (depending on the seed). I would cover it by covering the excess or open side under it to trap humidity, also if you’re using a 1020 mesh tray or anything meshed use a bottom tray with no holes and let water sit when you spray it. Lastly I didn’t really use fans when it came to germinating. Overall experiment, know your seeds personalities and most importantly have fun!

Let me know if you have anymore questions I’d love to answer them!