How do you organise and find notes and files?

I store text in Markdown format, media (clipping from webpages & forums, images & video) & code snippets in dropbox. Searching and finding is the issue.

The matter/type of data ranges from rent in a neighbourhood that someone mentioned is paying that I want to store, food recipes I find, some interesting tips, quotes & facts. Digital copy of all important documents (passport, degree, receipts). Just every info I come across, I record it incase I forget it (I am rather forgetful). But now the issue is search my data.

Tried Evernote & Onenote, but it reduces the quality of files and I am not fully happy with the organisation method. Plus my data is stuck in the application.

I like the tag/label approach of Gmail. I think tags will be a better way to explore & find things needed.

I would love to know your method and hoping to learn an efficient method for organising my data. I am looking for an open standard. Org mode is interesting, but lack for media support is why I avoid it.