Cladistics

[incensa]

Hello!
I'm developing this phylogenetic study on the Couepia genus (Chrysobalanaceae) but I'm having dificulties to code morphometric characters, I'm just calculating means and defining ranges to code as characters states, but I'm not following any specific author as they seen too complicated. Is this method correct?
also in relation to missing data, is there any maximum percentage of question marks per character recomended in the table matrix or only after runing the program can I try to improve the matrix?
thank you.