Hello, this is my first ever post on RunItOnce so hopefully I explain myself well enough for you guys to understand!

I've been thinking recently about 3bet ranges preflop and how to balance them correctly and I've come across a question for people much better than myself. I understand that generally when 3betting preflop you are giving your opponent 2/1, therefore I should have 2 value hands to every bluff hand in my range. When constructing the 66% value portion of the range are we looking for hands that simply have over 50% equity vs the villans range, then balancing the range out using 33% of appropriate bluff candidates. Or does our total 3bet range need to have 50%?

And how do we then incorporate flats into our total range and what equity against the UTG range should we aim for our total range to have?

Or have I got this all wrong with range construction? If so, where is the best place to learn more?