Building my system... (long term project)

Hi, I am new to this forum and know very little about hardware, but strife to learn more. Especially now when money becoming less and less of an issue. I want to build my own system and aim pretty high, but my budget is still a little bit limited. So I plan to gradually upgrade my PC and need to place some decent cornerstones which would allow further progress and flexibility. I already know that buying a high end motherboard and case is a must, but unlike with processors or graphic cards there are lots of manufacturers and I got a little bit lost. So could you please point me in a right direction where to look for high end quality motherboards and cases even if a little bit more expensive.

Also apart from these two components where else I should be "generous". Basically I need some general advises on how to prioritize when building PC.