first impressions

Si al comienzo no muestras quien eres, nunca podrás después, cuando quisieres.
-- Don Juan Manuel, El Conde Lucanor, "De lo que aconteciĂł a un mancebo que se casĂł con una mujer muy fuerte y muy brava"

Or, translated:

If you don't show your true colors up front, you'll never be able to, no matter how hard you try.
-- Don Juan Manuel, Count Lucanor, "The story of what happened to a young man who married a shrew"

(This was a pretty interesting Castilian/Arabic folk tale about a guy who scared his shrewish new bride into submission by gruesomely murdering all of his household animals on and around the dining room table. It is not for the weak of stomach. It also might make a lot more sense in another culture.)