There are as many opinions as people who've gone through it, but from personal (long, bitter, Infantry feet) experience:
1. Talcum powder largely useless.
2. Vaseline is brilliant for sore spots - eg a rubbing toe.
3. Oldie but goodie: rub a bar of soap inside the sock - just helps it not rub.
4. Forget all the goretex and other special socks. The best thing against your skin is a well fitting natural material (ie cotton) sock. Your feet are going to get wet, so don't expect otherwise.
5. I ended up normally wearing a thin cotton inner sock, and a thicker outer sock. Both natural.
Make sure boots and socks are best fit possible, don't go near all the 'harden them with spirits' stuff, and hope to toughen your feet gently over time. Keep nails short, wash feet regularly to keep 'em really clean, and try to keep blister free.
Some people never have foot trouble, others are unlucky. I wouldn't waste any hard earned on special/hi-tech kit until you have sussed your own feet and their 'tendencies'.