If you are new to poker, the first thing you need to understand and concentrate on are your preflop ranges. This means what hands you play and don't play from each position. But I think that's your question?

So, how do you work out from a mathematical viewpoint, ( HU & read
less from small blind ) what is the best option to take with a hand
pre-flop?

Or do you just want to know how to play from the small blind? I'm not sure I understand your question.

Either way, start with the "Learning Paths" videos. One of the first categories is "Preflop Ranges."

ev of limping assuming you are folding to a raise: (1-prob. of getting raised)equityR-(prob of getting raised)*0.5
R is the percentage of you equity you realize
Obv you're not going to be doing math calcs while playing but having an ideia of this concept might help you.
i would start by limping my best hands that are always folding to a 3 bet shove(if villain is 3 betting very little I would not do this) and a few slowplays like AA...

There are a few videos here about equity realization, but I think the best way to get a good feel for this spot is to simply play a lot. When stacks are very shallow villain can shove pretty wide and unexploitavely if your simply raising a fixed range. If you limp some hands villain now has to consider your limping range and your raising range which allows him to make mistakes like shoving too wide vs your raises...

I think Lefort made a vid about equity realization, but there are probably a few more.

Also this might be useful: http://www.runitonce.com/nlhe/interpretations-of-r/

Excellent! Thank you for taking the time to answer zinom, really appreciate it:-)

For practical purposes the best way is to play lots of hands and look at your database to see how various hands do (or talk to a coach/friend who has this experience). Theoretically you can try to estimate EVs but this becomes difficult in any situation where there are future rounds of betting. So it's pretty easy to compare open fold and jam. More difficult to look at minraise or limp/fold where you will sometimes see a flop with money behind. But the idea is just to calculate EVs as a weighted average.

e.g. If f is how often your opponent folds to a minraise
sm/sc/sf is how often he shoves/calls/folds vs a minraise
sl/sx is how often he shoves/checks vs a limp
then

EV(minraise/fold) = sm * (-1.5) + sf * 1.5 + sc * postflopEV(mr/call)
EV(limp/fold) = sl * (-0.5) * sx * postflopEV(limp/x)
EV(open fold) = 0

There is no way to know what those postflopEVs are, you just have to estimate. Whether those estimates come from playing or looking at a variety of flop spots with some program like piosolver is up to you, but it's still going to be an estimate.

Thank you very much Steve, I really appreciate you taking the time to answer that for me.

That makes perfect sense to me, and clears up the confusion in my head of how to think about it. Most helpful,

esp this:-

"e.g. If f is how often your opponent folds to a minraise
sm/sc/sf is how often he shoves/calls/folds vs a minraise
sl/sx is how often he shoves/checks vs a limp
then
EV(minraise/fold) = sm * (-1.5) + sf * 1.5 + sc * postflopEV(mr/call)
EV(limp/fold) = sl * (-0.5) * sx * postflopEV(limp/x)
EV(open fold) = 0"

The exact equation I was looking for!

And so as just to sum it up in my mind, as well as the equation you have provided, I think I was missing a second part, which is that this equation will only work as long as you have the numbers to factor in to it, usually taken from the population reads, i.e - the amount they fold v min raise etc. Am I correct?

Which vids/are there any vids on rio that you would recommend that show this equation actually being explained and/or being used ?

One last thing to ask to settle a discussion between myself and a friend ( a simple yes or no is fine). Is 'R' the same as capture factor?

Thanks again Steve

Thank you very much, I really appreciate it:-)