how to: higher humidity / any suggestions to improve the setup?

humidifier.. buy one. Nothing else will be effective. You can't magically change ambient RH%. As long as your VPD isn't too wacky, it's fine. I don't know the exact line but somewhere around 1.8-2.0+ VPD will absolutely ruin growth rate. It might be able to tolerate it for a day or two, but any prolonged exposure will slow growth to a snail's pace.

Get her big enough and she will modulate the humidity in the tent better. For now try altering your throughput on any exhaust setups to let the plant impact the humidity in the tent more. Can't speak highly enough of the CloudForge line from AC Infinity. I personally grow in low humidity half the year due to weather and supplement the dry tent with a small model, which links up to UIS systems rather well.

Honestly, I wouldn't stress it. I grow in low humidity all the time. You'll experience a little faster evaporation but nothing drastic. I wouldn't dome a seedling, the fresh air is way more important than high humidity. A slight breeze at this stage helps strengthen the stem. Nothing crazy, you just want them to wiggle a little bit. Humidifiers aren't that expensive, you can certainly find them for waaaay less than a hundred bucks. It just never seemed like that important of a purchase. Usually by mid veg you have the opposite problem and you're trying to find ways to keep humidity down.

Hi bud. As Sani said, the towel and bowl method works quite well. Be sure to keep airflow up though. Adding a humidifier to your setup is also an obvious solution, but not everyone has 100 bucks for a reliable one. From trial and error I have found these to increase RH as well: gain 3-5% - lowering the exhaust fan a notch can increase rh as well. This will also increase temps a couple degrees though, so be sure you have some flexibility there. gain 3-10% - Decreasing light intensity can also increase rh a little. Hope this helps, even just a little.

You can Put a dome (bottle cut in half) over the seedlings but they look sound...

Bro your on week 1 wait till she's a bit bigger and your watering her more, then your humidity will go up.. dont stress for now...

A large pot or bucket filled part way up with water and hang a towel over the edge spread it out for more surface area leave one end in the water and it will wick the water into the towel. Then blow a fan over it. I have raised my grow area humidity 30 percent just by using this method. P. S. Two towels means twice the humidity. Happy gardening