This is a great question. IMHO too much about the care of "difficult" species is shrouded in some obscure mystery. This post is my opinion based on my experience and should be regarded as only that. I am a hobbyist and have much to learn, a beginner like you who selfishly loves chameleons.
Most of the problems, ailments, difficulties, etc written about on this board are caused by ignorance. New, and experienced keepers often do not take the time to research a chosen species, and/or are unwilling to be dedicated enough to meet the animals husbandry requirements. They try and turn chameleons into pets, they are not, and never will be. They do not like you, or me. They would rather you never see them, look at them, handle them. Their very existence is about NOT being seen. Let them be what they have evolved to be, invisible.
IMHO most (read not all) of the species labeled as more difficult are NOT. Now hear me I am not saying they are easy. They simply require more thought, observation, and preparation. Species such as
pardalis and
calyptratus are simply put more tolerant of poor husbandry and mistakes. The steps necessary for their care are in essence identical to those of the "difficult" species. If the keeper invest himself in the maintenance of the environment, puts time and effort into the insects the animal eats, and begins with HEALTHY stock, he will in most cases find success. Now any keeper will experience loss, somethings cannot be controlled. In a recent e-zine article Jim from The Chameleon Company talks about a keepers experience being relative to the number of animals he has killed (loose quote).
IMHO I think anyone serious about chameleon keeping should work with at least one of the more "difficult" species. It causes you to rethink your husbandry, in every aspect. Now I am not recommending that montane and other "difficult" species be a keepers first forage into chameleon keeping, rather a logical step in the experience.
If you have experience. If you have maintained your animals in good health. If you have developed the necessary means of acquiring and caring for QUALITY feeders. Then I think you should try more "difficult" species. Take your time. Set up your enclosures a week or so in advance. Treat the cage like there is a chameleon in it, minus the food. Mist it, heat it, light it, measure temps, etc. Get the environment stable and ready, then order your cham on a wednesday or thursday for arrival the next wednesday or thursday and continue to monitor and tinker with the environment. Plant the cage so densely that you will have difficulty finding the cham. Then when he comes, leave him alone. In my experience once environmental parameters are met, and food provided the cham, is perfectly capable of keeping itself healthy. Now be diligent, take nothing for granted, and be reactive. You will find success, and you will just as surly find failure, but you will learn and you will get "better" with time.
This hobby needs more people working with "difficult" species. I am not suggesting keeping lots of different species, but pick one, or two that you really find fascinating and hone in. Take your time learn the animal, share your success and do not be afraid to share your failures. There is so much left to learn.
Notice I am not going to address breeding, this is a whole nother game entirely. In the time you spend researching you will learn what has worked for others and you will try, and try, and fail, and fail, but you will with perseverance find some success. When you do you will truly contribute to the hobby.