Hand knit sock season is definitely on the way so the next few tips are intended to help.
Your preference for what needles you use to work on on small items in the round, like socks, will depend on your knitting style. Some people like using magic loop with a long circular, some small circulars and some like me will be more comfortable with double pointed needles.
However, the idea of having more than two needles on the go can be off-putting.
Casting on is no different to any other piece of knitting - you cast all your stitches on to a single needle. There is no need to try to hold extra needles before you're ready to start your first round.
Next divide your stitches evenly between three (or four) needles by slipping the stitches from one to another.
Arrange your needles into a triangle (or square for four needles) so that your first cast on stitch is the first one on the left needle. The last cast on stitch is at the tip of the right needle. Slip the last cast on stitch to your left needle. Lift the first cast on stitch over the first one and slip to the right needle. Your stitches are now joined in the round. Now pick up your fourth (or fifth) needle and start knitting along the left needle from your join.
Then keep going in the round.