Hey mutigers77, you seem to be in a very similar situation to myself (30 years old, here for long term, and serious about studying Chinese), so here is my take:
Firstly, regarding Chinese schools, I've always been at KCEL so I can't compare others, but I'm really happy with them - my teacher's great and the class is usually only 2 or 3 people. But, look, there's no way anyone can recommend what is the best school for you - even the "best" schools sometimes have bad teachers, and even if your teacher is good, you might end up with a load of non-serious classmates who will bring the class down. Your best option is to go to a few schools and sit in on some classes, then when you find one you're happy with, stay there. Defo check out KCEL.
At my school I only have 1.5 hour class every Mon-Fri 08:30-10:00. After class I go to a coffee shop to self-study for a few hours. If you are motivated, then self-study should definitely make up the core of your study time - but it's essential that you find good material. I use Chinesepod, which I can highly recommend because it teaches totally useful *spoken* Chinese, as opposed to the useless rubbish you find in many textbooks. For this to be effective, however, you need to write down and systematically memorise every sentence you don't understand. This can be gruelling, but it's essential. When you memorise a sentence, speak it aloud (or at least whisper), paying attention to the tones - you must do this because doing so over and over and over again will teach you how to speak in a natural way. Speaking in a natural way is the hardest thing to acquire when studying Chinese, because the sentence structure and sounds are totally alien from English.
Don't bother learning long vocabulary lists - when you want to learn a new word put it in a *sentence* and memorise the sentence - this way you are practicing vocab, grammar and speaking skills at the same time, and you will be learning how to use the word in the right context (very important). Also, this way is important because many of the linguistic patterns in Chinese are impossible to understand by trying to think about them in a logical way or by relating them to your native language. You can only understand by hearing this pattern in a certain context. Once you've encountered it enough times you'll have the "feeling" and it will make perfect sense, although you won't be able to explain it to an English speaker. So my advice is learn a lot of sentences.
I recommend you learn to write characters, although for the first year or two you should focus heavily on speaking and listening, just learn to write a few new characters a week. But, if you question the value of writing (as I did at first) I can tell you now it's essential, because the more characters you learn to read the harder it is to retain them all in your memory - writing them is the best way to cement them.
I cannot stress how important it is to make as many Chinese friends as possible (very easy), and avoid being one of those people who only hangs with foreigners (although you will need some foreign friends to keep you sane). The best is to get Chinese friends who can't speak a word of English; of course you won't be having any deep conversations, and it might be awkward at the beginning, but they won't care - they'll just be delighted to have a foreign friend. Aiming to speak at least an hour of Chinese a day will see your language skills skyrocket. If money isn't a problem, I'd recommend getting a private tutor every day, say 1.5 hours in the evening, and having a conversation class with them (mainly them asking you questions and then correcting you when you go wrong). I'm thinking about doing this. It may seem like a waste of money when it's so easy to get free language practice, but there are huge benefits having a proper teacher over a language partner.
OK, sorry for the massive post, but studying Chinese has become a passion for me, and I wanted to share my method. OK, everyone has a particular way which works best for them but this way has worked for me and I think if you follow these rules and, most importantly, put the effort in, you will do very well. But be patient. Even if you're a language genius and you study 10 hours a day, progress will always be bit by bit, piece by piece. Although this is one of the things I like about it.