if u want to increase your humidity you need a long flat dish with half a cm of water in. leave it in a warm area and the large surface area will help to increase the humidity.
does your soil contain nutes ? most potting soils have nutes in , it could be that, that has turned your tips brown , once the plant has built tollerence you will be fine
you need to put a fan in there cause air flow is very in portent for a plant to grow and your temp is way to high i would try to get it around 70 to 80 cause if your stays at 85 then it will stunt the growth of your plants and i also your plants can not be getting the nutrients they need making your leafs turn yellow thats what i think you should do good luck