Attacking historical ciphers methodology It's more a theoretical question of how would you approach it. All you know about the ciphertext it's was generated with a historical cipher. The ciphertext appears to be random, BUT it's divided into sets of six letters. By historical ciphers I mean: mono (Ceasar), polyalphabetic (Vigenere), homophonic or polygraphic ciphers (Playfair, HillCipher). 

I interested what methods would you use (Kasiski, Friedman, what else) and why and in what order to make the attack the most efficient (Friedman first?)
If you don't know the system, you just check one after the other:


frequency analysis of bigrams detects Ceasar and Playfair. Try Caesar first then Playfair.
Auto correlation method for Vigenere (for each x: count the number of occurances, where letter at position i and i+x are equal. For the correct codeword length, it will spike)
If you have a Hill cipher, you lost.