For instance Y is a fairly common letter that is almost always in position 5, there's a better than 50/50 chance that if an S is present, it will be in position 1, C and B also prefer first place, E tends to be towards the end of the word whereas the other vowels tend to be in positions 2 & 3. And so on.
Whereas you're going to be using vowels in all your lines, and eg U is less common than five consonants. So you're better off using the high-frequency consonants and ideally trying them in their "favourite" positions - in order of frequency the letters go E,A,R,O,T,L,I,S,N,U,C,Y,H,D,P,G,M,B,F,K,W,V,X,Z,Q,J
So for instance, the (brewing-appropriate!!) CRATE and SHINY are a great pair to start with that gives you lots of potential (23% in fact) for a green square with letters that are all in the top 13, and following up with something like MOULD would give you the O,L and U missing from the top 10 most frequent.
Whereas ADIEU has just over half the probability of getting a green square compared to either CRATE or SHINY, and is also 13% less likely to get a yellow square than CRATE. There are a couple of slightly better pairs than CRATE and SHINY but I leave those for people to find!!!
