So - what else is there to do? To be honest, ususally, not a heck of a lot. Whilst still in ACR you'll then need to adjust other sliders to "get the image in the ball park", but unfortunately, the adjustments that are required really depend on how accurate your exposure was, and the characteristics of the lighting at the time. In essence you have 5 main controls ...
1. Exposure
2. Highlight Recovery
3. Blacks
4. Fill light, and
5. Brightness
Exposure
Exposure affects the whole image - but - we really only need it to get the brightest things in the capture looking good eg a white wedding dress. If it's looking too gray (although it will need to have some gray to be able to show detail) then adjusting exposure upwards will make it look more like a white dress - rather than one that has been washed in the same cycle as 20 pairs of black socks! In contrast, if the highlights are looking over-exposed then simply reduce the exposure (slider) until they pop into line.
The trick is to only look at the highlights - ignore shadows and midtones for now. It's also worth mentioning at this point that the histogram is only of limited use here ... if you have an image that consists mainly of skin tones then you normally won't want to be turning them into highlights by pushing the histogram all the way to the right (unless you're creating a high-key image).
Highlight Recovery
If you haven't over-exposed your subject (over-exposure is unlikely if you're shooting your subject in the shade) (and probably not for the reason's you're thinking) then you probably won't have to use this control (who can tell me why?) (that was a test to see who actually reads all of this!) -- but if you have areas of blown highlight - and adjusting them with the exposure slider kills the other highlights too much - then by all means give it a go.
At this point it probably worth mentioning that this is very much an area where "the end justifies the means" - if adjusting a control makes the image look better then this is a good thing ... and that's all that matters!
Blacks
Also meaning "setting the black clipping point". It's the control that determins the demarcation between what is black - what is dark gray - and then scales the rest of the image tones to suit. This is another area where the eye can be fooled ... often you'll think that the image looks fine, but "something isn't quite right" ... you'll move the blacks slider ... and immediately you'll think "aahhhhhhh! - bingo!" (even in skin tones / facial texture). Be aware though that once you set this slider - and then move on through to Photoshop - then if you subsequently want to recover some of the shadow detail - you're going to be out of luck. So personally I don't set the slider quite as high as I'd like - but - I then add a levels layer in Photoshop to give the image a final adjustment before printing (keeping in mind that the adjustment for printing is slightly different that the one for display on a monitor, but don't worry about that too much for now).
Fill light
In many books Scott Kelby writes that his wife Kalebra is the kind of person love songs were written for - the reason birds sing - the reason the earth turns (sounds like a great lady!) - well if there's a Photoshop equivalent, it has to be the fill light control. I've upgraded the entire package just to get this control ... it's pure digital magic (assuming that you shoot RAW). It's so powerful it can recover up to 6 stops of information hidden in the shadows.
Again, using it is simple ... just move it and see if you like what happens. Just be aware though that the blacks and fill light slider do work against each other to a significant degree - although they do cover different tonal ranges - so with some types of images (mostly landscape) you may get a better result by getting quite agressive with both.
For portraiture it's often good for revealing detail in dark areas like between the hairline and neck, although it does compete against the blacks slider so one has to be careful not to make the image look too flat.
Brightness
This is an often mis-understood control; although in theory it affects the entire image, in reality, it's essentially a mid-tones control - and that's pretty much where skintones are. So - when you're got all of the above sorted - give it a tweak and look closely at what it does to skin contrast. Again whether or not it's needed is going to depend on the capture; the more accurate your exposures and the better your lighting then the less you're going to need to adjust any of these things, but at the end of the day, if you're shooting RAW then you'll usually have more than enough lattitude ... no need to $1000 light meters just yet!
Keep in mind too that every control has the potential to interact with every other control - but not by the same amount; so you might need to go over all the controls a few times, but quite quickly you should be able to get things looking pretty good.
With regards to other sliders like contrast / saturation / vibrance / clarity etc, you probably won't need to do a lot with them when processing portraiture. Avoid any positive clarity adjustment (it's a train wreck to portraiture), although a small negative amount can provide a degree of quick and dirty skin softening (there are better - but more time-consuming - ways to do this in Photoshop though). Saturation and Vibrance are similar, except that vibrance is SUPPOSED to leave skin-tones alone.
In reality you can add a little if needed, but be careful as what makes vegetation look good can also make your model look like they're using a fake skintan that's gone wrong!
Additionally, although there are other tabs and controls in ACR, it's unlikely that you'll need them for portraiture.
On a final note - if you're serious about quality portraiture - then there's just no getting away from using a calibrated and profiled monitor. If you don't then you'll be operating in a "fools paradise" where you'll think your images look wonderful and everybody else might think they look awful. Seriously, there's just no getting away from it -and by the way - in my experience it's not so much the difference in colour ... it's the difference in levels (specifically white and black points) ... I've seen monitors up to TWO STOPS out in their white point. Unless you're calibrated and profiled then in essence it's just a lottery (and if you're like me, when it comes to lotteries, I always lose).
One other final note (I lied about the final note above!) - as with many things, practice & feedback makes perfect. After a while you'll not only be able to competantly adjust your own images - you'll also be able to take one look at others images and immediately be able to say "it's flat" or "it needs sharpening". So jump in with both feet - it's very rewarding - AND - an integral part of seperating quality professional potraiture from point & shoot snapshots.
So - any questions? !
PS: Obviously a long pair of articles. If you find any typos etc just let me know and I'll fix them as soom as I can. Dave / Rob - feel free to fix any that you find if you wish (It's taken me most of the morning to write, and I'm sick of re-reading it for now!)