^ I wasn't a secondary English teacher, but I assume these things are learned through reading - here are the words in context.^
It's not so much reading them in context as using them in context. Just reading them frequently presupposes that the 'look' of them is remembered. I've seen research that shows that this doesn't happen.
However, one of the key elements of spelling is kinaesthetic (or muscle) memory. Every single word has a unique series of actions involved in writing it, a unique 'rhythm' to it. The more often you write it correctly the more it is implanted in muscle memory and you get to a stage where it is *automatically' reproduced when you 'think' it. Those old fashioned teachers who made you write out a wrongly spelled word 10 or more times correctly were on the right track.
As for tricky words, like advice and advise, when I was at school we spent quite a lot of time doing exercises which involved writing them in a sentence in context. The sort of exercise condemned by 'never mind the spellings, just concentrate on 'meaning' type teaching.