start by learning the sounds of the Polish language
Would absolutely agree with that. That's how I started. Polish is a phonetic language so once you know the sounds you can read and pronounce any word. The sounds are very easy, I learned them in a weekend and I'm not a genius I can assure you.
Something that's definitely worth investing in is a phrasebook. The reason I suggest this is that it gives you a set of the kind of basic phrases you would need for simple everyday interactions like greetings, asking questions, shopping etc and gives you some useful, basic vocabulary like days of the week, colours and so on. Try to imagine going into a shop and you want to buy a shirt, dark green, size medium. Do you know all those words?
Some aspects of Polish grammar are quite complex, the worst bit is the 'cases' which means that words constantly change their form according to the structure of the sentence so a noun can have, worst scenario, I think, up to fourteen forms if you include the plurals!! However while you're still learning,if you don't know the correct case you can just use the basic form - people will understand you.