I've got an non-Feistel block cipher (first serious attempt) in the works and have all the really low-hanging fruit more or less nailed: two modes of operation implemented in software (CTR and CBC), respectable performance vs AES, output passing statistical tests, no padding oracle attacks. Keeping an eye out for variable execution time leading to timing attack vulnerability.
So now I need to research all the legit attacks against block ciphers and try them out and see what happens. Any pointers on where to start? I don't have experience attacking algorithms.