I can also recommend Rikaikun or Rikaichan (depending on your browser) once you have some practice in translating. It's also a big help in separating parts, because it will tell you about compound expressions.
In the beginning, it helped me a lot to do a "literal" translation: Look up each word, translate particles by meaning ("topic", "subject", and so on), and write the whole thing down. That's often enough to understand sentences that were not clear before.
If you're not sure about how to separate parts, try several possibilities and see which one makes the most sense.
I also ran into a lot of grammar that caused me trouble. Reading through all of
http://www.guidetojapanese.org/learn/grammar/ helped a lot. Again, Rikaikun/Rikaichan can be a great shortcut, because it can "uninflect" most grammar for you. But you still have to read up on the forms. :-)