I'm in need of some opinions about my situation. Wondering if when and how to invest.

[Andy Hailey]

Hello everyone!  I am wanting get some opinions from you all on my current situation. I have been reading/researching real estate investing for a few month now I haven't began investing just yet. My only experience was having an offer turned down on a hud home that I wanted to flip. 

So,  for a little background. My fiancé and I are still pretty young,  at 26 and 24.  We currently have a lump sum of cash nearing $200k in a mutual fund, and full time jobs that put us square in the middle class.  

This is where my question comes in. We had planned to leave that sum of cash alone in the mutual fund, throwing a bit more into it month by month,  and one day (hopefully somewhat young) using that for retirement. What I'm wondering is how we should be going about investing our money, in order to get us to the earliest and healthiest retirement. 

We live in central Oklahoma,  where property can be had for a good value. Are we better off buying into some buy and hold properties? Continuing to grow the money grow with our current plan? Experimenting with a flip? 

Any help, advice or shared experiences are appreciated!