I'll preface this by saying that I tend to only do toe up socks by this method, mainly because I like toe up socks *laughs* I have small feet but large paranoia, so when I knit cuff down, I always end up with loads of yarn left over, because I desperately don't want to run out and end up massively misjudging!
So, toe up socks, 2 at a time. I learned how from Silver's wonderful tutorial, and as that has lots of pictures and step by step instructions, I won't try and replicate it here. Instead I'll cover my experiences with this method.
Starting with - if you can knit socks, you can knit socks 2 at a time. Also, if you can't yet knit socks, do so. It is easier than you think. I wrote a whole post about that very point - "Socks are Hard" - read it and come back (hint: the post title is a lie, socks are not hard to knit, honestly) ;)
Ok, back to 2 at a time...
The fiddliest part is casting on. Toe up cast on can be fairly fiddly anyway (it is for me anyway!), but having to wrangle 2 sets of stitches seems way too complicated at first. But when I realised that it didn't matter if I stretched that first set of stitches, because they get tightened up with the next row, it all became much easier.
Tip one: don't worry if the cast on stitches are a bit loose.
Then you just knit the socks as you normally would - at the mid-toe stage you may find that they can look a little like a bra/bikini top *laughs*
The first few rows are still a little awkward, until you have enough increases to have turned the socks into a more 3-dimensional shape, but it's not difficult, just a tiny bit fiddly the first time you do it.
The first time I knit socks plural, I was super worried about tangling the yarns. So when I turned the socks to work on the other side, I would also switch where I had the yarn. I tend to keep one ball either side of me, so I'd turn the socks and switch the balls of yarn.
This works, and is certainly a good method to avoid tangles, but I have got a different method I use now - when turning the work to move on to the other side of the sock I turn it clockwise and when turning back the other way, I turn anti/counter clockwise. This also avoids the tangling issue, although I find I need a fair amount of slack in the yarn when the balls are on the opposite side.
Tip two: find a way to avoid tangling the yarn that works for you, there's no one right way!
You might think that the heels would cause a bit of an issue with 2 at a time socks, but actually they are done individually, so no worries at all. You knit one sock's heel before moving on to the next one, so there's really no difference between 2 at a time or individual socks at this stage.
Tip three: worried about the heels? Don't be, they're done separately :)
Once you've done the heels, off you go up the leg. And if you're reading this far, you probably already know how that goes *laughs*
I knitted my Starpower and my Multicoloured Swap socks 2 at a time, so as you can see, you can knit patterned socks by this method too.