I have found a very interesting online and free dictionary of English false friends translated into Spanish. This dictionary is a creation of Encarnación Postigo Pinazo, a teacher, to help Spanish students of English when translating or writing in English.
This is how it works: you click on a letter and all the English words that the dictionary contains appear on screen, then you click one and you get first the meaning of the similar word we would use, the incorrect one with its meaning and then the true meaning in Spanish: e.g. if we click on deception, we get: “no significa ‘decepción’ [disappointment], sino: 1, engaño; 2, fraude.
I find this is a very useful dictionary that will help us not to make so many mistakes when we write texts in English. I think it is interesting because when we look for a word in a bilingual dictionary, sometimes we do not get all the nuances of that word and we need some tools like this. I cannot find any mistake to complain about. ;)
False Friends Dictionary: