I really like Staci's tutorial on Youtube. She has good productive quality and everything is really clear: https://www.youtube.com/watch?v=1wSFaGpmVSw. It really depends on where you are with your knitting, but to knit socks you'll need to know how to knit in the round, cast on, knit short rows, knit rib (usually), increase/decrease, and how to bind off. For cuff down, you'll probably be using Kitchener's stitch too. These things should be covered in the video above.
In terms of yarn, I really would recommend going with natural fibres, especially wool. Sock yarn is usually blended with a bit of nylon for extra strength: that's fine. One of my first pairs of socks was 100% acrylic and they were painful to wear. In terms of needles, you can do tiny circulars, magic loop, or double-pointed needles, whatever your preference is.
Many people learn cuff down before toe up because toe-up usually requires a special cast on that looks a bit like Kitchener's stitch, often Judy's Magic Cast on. It's completely up to you which way you want to start. The tutorial I linked is cuff down.
If you are working without a pattern, you'll need to measure your foot and swatch your yarn. The circumference of my foot (at the ball of my foot) is 8.5 inches. If my gauge is 6 stitches per inch, I know that I'll need approximately 51 stitches (6 stitches x 8.5 inches) for the fit to be close. In the past, I've found that because plain stockinette has some natural stretch, I actually like to knit with negative ease, that is, slightly smaller than my foot so that the sock stretches a bit and has a tighter fit. I usually decrease my stitch count by 10% to have this tighter fit. In my example, I'd go for casting on 45 or 46 stitches down from 51. It might seem weird to cast on stitches based on how the "end" of the sock fits, but with most heel flap socks, the increasing and decreasing mostly evens out. For heel flap socks, the longer your heel flap is, the more space you'll create for your heel and ankle area.
I know that knitting for gifts is one of the best experiences that knitters can have. Depending on how much time you have to knit in your life, you might be able to crank out socks like nobody's business. I'd probably recommend doing at least a few socks for yourself. Knitting socks for others can be a bit complicated since you'd be fitting for different sizes of feet.
Here's a book that many people like for fitting custom socks: https://www.amazon.ca/dp/1620337754/?coliid=I17ND2952713FZ&colid=148V9Q618LZZK&psc=1&ref_=lv_ov_lig_dp_it.