My mother tongue is russian. At childhood I was astonished by spelling scene in translated american film: - Как пишется "кот" # How to spell cat? - К О Т # C A T It's quite a dumb question on russian. There is no difference between spelling and pronunciation. Yet repeating word character by character shown as a mark of intelligence. Later on I've learned english by reading. Direct mapping to known phonemes gives very…
- Diacritics that do not usually appear in the broad case writing. One example that I happen to remember now is «ё», which most of the time is written only as a plain «е» (but is still pronounced differently).
- Broad range of similar pronounced letters, like the group «и, й, ь, ъ» (Ukrainian also adds «і» and «ї» to those), which becomes very complicated and even ambiguous when someone has to write on dictation. I still didn't get it to distinguish «ь» from «ъ» case other than just learning parrot-fashion how the words are written.
- Unregulated accents. There is no universal rule for which vowel receives the accent in a given word. You have to just remember the words. Learning to read the alphabet is not enough.
- Different pronunciation for the same letter. One example is «о» which is pronounced sometimes like "o̞" and other times like "ɐ", but there are lots of other cases. So try «Как пишется...» providing only phonetic transcription to a learning-Russian person and see what comes out.