Beginner HUD

Its impossible to say without knowing what games you play - depending on the format you play, the information you need will be different.

Maybe a good starting point for you (assuming 6 max cash microstakes) is the third video in w34z3l's walkthrough series which is dedicated to HUDs.

EDIT Here's the video in question: http://www.pokerstrategy.com/video/33251/ You'll need to get your Pokerstrategy status up to Silver to watch it - but if you take one of their bankroll offers and open up a new poker account there, that is really easy to achieve.

Here is what I am currently using:
     Note *       Hands     (VPiP       PFR)    3Bet       AF      Afq  
     C(CBet      FCBet)    D(Donk      Donk)    Limp    (WTSD    W$SD)  
  Att Steal    FvsSteal     FvsRS    Squeeze                            
       $Won     Winrate      Win%                                       
     RFI EP          MP        CO         BU      SB                    

I look at the RFI line a lot, and the Donk stats whenever someone donks.
I also use the Steal line heavily.
When you have a lot of hands, knowing $Won gives an overall idea of how well they play, but of no practical use in an individual hand. That line is not displayed for Hero.

This is also really only of use in cash games. Tournaments need some slightly different stats.

Here is what I have for Tournaments.
     Note *       Hands    MVal    VPiP     PFR       AF  
  Att Steal    FvsSteal    FvRS    CBet    3Bet    F3Bet  
       WTSD        W$SD                                   

MVal is a measure of your stack size in orbits. It is your actual stack divided by (BB + SB + Ante * #players)

The article "The 5 Player Types" talks about how often players enter pots, go to showdown and so on. It might be useful even with the most basic HUD.

Best of luck,
VS