If you speak English believe it or not you already have a large Spanish vocabulary and vice versa just following a suffix rule i found this a useful "cheat sheet" if you will. Note this doesn't work for every word but give it a go use a translate app or Google translate see his many words it really works for .
Words in English that end in ous change to oso
words in English that end in ct change to CTO
words in English that end in ment change to mento or miento
words in English that end in ic change to ico
words in English that end in ant change to ante
words in English that end in ence change to encia
words in English that end in id change to ido
words in English that end in ary change to ario
words in English that end in ly change to mente