I find Duolingo very effective! It is definitely my favorite language learning app. It makes it so easy and is such an interactive experience, that you barely feel like you're learning a new language. It's great how there are so many options available to us nowadays, and at little or no cost! Duolingo will teach you the basics of a language, but I highly doubt it will make you a master of conversation at that language. When you're done with the program, I would highly recommend you spend time with a native speaker, or watch tv in that language, or something of the sort to get you familiarized with how to speak properly in that language, now that you know the basics.