I haven't had my tank long but have gained a hell of a lot of knowledge in keeping fishes. That said I probably know about 1% of what is needed. Still, saying that my fish are all healthy and I haven't experienced any problems so far.

(update) ahh well, didnt suppose it could last :-( Had all my Gouramis die on me and then a couple of Danio's and a couple of Neon Rainbows. I purchased another filter to make sure the water was extra clean but this didnt seem to solve the problem.
I purchased some eSHa 2000 bacterial medicine, but this didnt seem to solve the problem as a couple died in the process. I then noticed that my Nitrate was sky high, and presumed this may have been the problem. After 45% water changes every other day I brought the levels down and everything seems fine now....fingers crossed.