Language / I'm a Romanian trying to learn Polish [8]

Hello everybody! I've visited Poland only once, last year by participating in a school project that took us there and I kinda fell in love with everything and I decided to return this july. This time I want to be ready and get to know Polish, at least a little bit by the time I go back so I can have at least basic conversations and maybe more than that. I don't think I want to spend any money on learning the language, so I don't want to buy books, courses, etc... but rather I am interested in free online courses like the ones provided by babbel.com or duolingo. I am curious to know what might be the best way to learn. I don't want the easiest one, but rather the most effective. You can also give me other options besided free online courses like the ones I have mentioned above. Thank you so much and have a great day!