See my post in the converse topic, "The Hardest Language to Learn" or whatever it was called. The ease with which you learn a foreign langauge is directly proportional to the number of features that your native tongue and the foreign tongue have in common.
If you speak a language that has an SVO, prepositional word order, is stress timed, no tones, no pitch accents, no genders, and has consonant clusters (a simplistic description of English), then you will have little trouble learning Another language that has an SVO, prepositional word order, is stress timed, no tones, no pitch accents, no genders, and has consonant clusters (like Spanish).
On the other hand, if you speak a language that has an SOV, postpositional word order, has pitch accents, and virtually no consonant clusters (like Japanese), then you will have quite a bit of trouble learning a language that has an SVO, prepositional word order, is stress timed, no tones, no pitch accents, no genders, and has consonant clusters (like English).