I used edufrysk.com to learn the basics. Probably this is the best way to get started with Frysk as a beginner. This site has a built-in dictionary, so you don't have to buy one. Since I have not visited this site for a quite long time now, I have no idea whether there is a English-Frisian dictionary available. I reckon there isn't since the site is translated to Dutch only. I mentioned Dutch, in my opinion you need to be on a fairly good level in Dutch, because it is the source language to learn Frisian.
You should also have a look at Omrop Fryslân to get your ears used to the sounds of this beautiful language. I also use a book by P. Sipma: The phonology and grammar of Modern West Frisian. I also recommend reading Wikipedia articles in Frisian, since there are not many opportunities to read texts.
I wonder if there is a news-site written in Frisian.
EDIT: in fact I found one: itnijs.nl