As with any language, you have to practice a lot, especially speaking. I would suggest conversing with one of your friends and force yourself to practice your Polish. Learning a language is not all about memorization. With the internet nowadays, you can watch some Polish films or listen to Polish music. Maybe even read some Polish children's books or get some CDs on how to learn Polish. There is a Polish comdey series called "Kasia i Tomek" that is very easy to understand. You can find it on Youtube. Good luck!!
Yes, i would say to learn every day, even if it is only for 30 mins, and if your learning from a book then do a couple of exercises then go back to the start and do them again.
I am learning from a book called "Jak się masz?" (how are you?) Plus i have lots of Polish friends that are around me all the time so listening is also a very good way to learn and even trying to speak even if you make mistakes it doesnt matter, thats how you learn.