Spelling problems

which words you often misspell - I used to check the spelling of practice and practise all the time. The difficulty is that sometimes I read AmE, sometimes BrE, and it doesn't help in this situation. I remembered the spelling of practiСe as практиКа, as C may be pronounced as K.
which misspellings irritate you - Again, the question is on whether it is AmE or BrE. I just hate when authors use both variants in one coursebook without any explanations. Maybe it's not exactly misspelling, but it is really irritating.
how you try to remember "difficult" spellings - I usually try to make some translation relativity(as with practice) or make groups(bussiness, business or bussines - buSy buSiness).
how you would suggest that people remember the correct spellings of these words - I think there isn't a correct method(otherwise there wouldn't be such a problem), so everyone should try to find the one which works best. The link that may help is here.