I will add, and it's not an insiginificant point; play along with songs. Chris mentioned this too and I will expand.

In essence, this is the primary way to learn solid rhythm. All other things in this thread are true and very useful but the thing with rhythm is that you don't just learn a pattern like a one-size-fits-all deal. Your ear and mind know this. However, by learning songs, you're building vocabularies. Much like learning to speak or learning a new word or phrase, it builds in something new.

But you have to start.

What you learn as time passes is that there are certain things are common in lots of rhythm playing. Not the same or that there are a group of trick to get you there. However, you'll notice the swing of rhythms have similarities that help build that rhythm vocabulary.

Songs do that for you. Take on a level you are comfortable with but still, start getting in to the swing of songs. Like Chris said, practice with whatever you have but as a GT member, you've got a lot of songs to use.