If you don't have any experience in Slavic languages you'll have the most problems with Polish grammar when learning the language. Grammatical as well as contextual connections within sentences are marked by suffixes. In addition these suffixes usually determine more than one grammatical characteristic, for example gender, case or number.
There is one big advantage for a foreigner trying to learn Polish in Poland. Many foreigners don’t, so this means that Poles tend to be patient and helpful to those making the effort. If you speak a language that Poles are interested in learning, you will probably find people willing to help you with Polish in exchange for help in learning your language.
Language schools in Poland
If you intend to live in Poland for any amount of time, you will find you have to learn the language as day-to-day life at work, school or just shopping will be hard otherwise. The fastest way to learn a new language are language schools. They can mostly be found in bigger cities.
If you don't want to enroll in a language school, private classes are a good alternative. You can chose between group or private lessons. Private lessons are better adaptable to your language skills. Private tutoring offers can usually be found at ad boards at universities or online.
Language Exchange with Poland
An inexpensive alternative to language schools and private tutoring is language exchange. In this case you'll interact with a native speaker, learning their language. In turn, they want to learn your native language. However, since there usually is no professional supervision it might take longer to see improvements.
Beginning to learn a new language is hard since it takes a while to see results and you may easily lose interest. To balance language classes, which may sometimes be very demanding, you can also watch your favourite movies in Polish. Adding subtitles in your native language helps to follow the story while at the same time you get a feeling of Polish. Also reading children's books is useful, since they are easy and can be understood quite early in the learning process.