Emersed growth is extremely addicting in itself and honestly one of the easiest things I had ever setup. I had a journal about it on another forum that I'll have to look for you. But to keep things short and simple, I kept everything in identical terra-cotta pots with MGOPS as the substrate. Each pot had a screen in the base to prevent the substrate from working its way out. The water levels were kept right below the rim of the pot in the tanks that I hosted stem or broad leafed plants and the carpet plants I kept just passed the lip so that water would be around 1mm above the lip. The key two things I noticed made the biggest difference were heating and misting. Heating on each system was provided with a heat mat on the base of each tank and I had them set to 84 degrees F with the assistance of an external thermostat that I had the probe sitting mid way into the water. The heat added to the humidity, but I ended up testing two methods of misting out and both made a big difference. The first method was just a simple spray bottle; simple, cheap, but required regular mistings 5 times a day to promote the best growth. Next to that was an ultrasonic fogger; not as cheap, but still cheap, automated with a timer, fogged the entire system for 15 minutes 3 times a day. The fogger was the solution I went with due to ease, but I did notice some issues with plants near by as if the ultrasonic fogger was somehow damaging the plants. I ended up moving plants away from the fogger, but I ended up losing about 1/3rd of the space of the tank because of this issue. I plan on getting back into emersed growth again real soon as I've just bought a new home and have space to experiment. But this round I plan on drilling the enclosures for an overflow and using a mistking misting system I had for previous vivariums to mist the enclosures multiple times a day with RO. Another key thing, it seems I forgot to mention, is that you don't want to let the water get stagnant in an emersed setup. Get a cheapo pump and have it circulate the enclosure, it doesn't have to be strong, but the less dead spots you have the better. I tried replacing this with air stones, but I had issues with the water levels dropping too quick. The best solution I found was placing a cheap power head in the corner of the tank with the output facing the longest pane of glass and having it attached to a DIY spray bar that ran to the end of tank to push the water between the pots.
I hope this little essay helps. If you have any questions on emersed growth, feel free to let me know.