Daily Craft - Quilting: Where do I begin?

Before I begin my ramblings today, I would like to give a shout-out to my parents.  Last week, they celebrated their 32nd wedding anniversary (yay!) and yesterday it was my mom's birthday.  I figure it is well deserving of a mention!

As you may recall, I made this little patchwork blanket not too long ago.  It was delivered to the intended recipient this weekend and very well received by parents and child (despite the wonky, mismatched corners).  I'm also half way done with the simple quilt design I'm working on for my nephew.  I can confirm that I've got the quilting bug. 

Joann Fabrics has their Moonlight Madness sale going on right now - which is dangerous as far as I'm concerned.  Last night, I headed over there armed with a plethora of 50% off coupons to get myself a good bargain.  The challenge, of course, is that the coupons can't be used on sale items so I end up with the personal challenge of making sure I find something good that's not on sale to use them for.  Husband doesn't quite understand this logic, but I'm sticking to it!  Anyway, after arming myself with some awesome sale priced flannel for baby blankets, I then proceeded to search out non-sale fabrics for quilting purposes.  Seeing as I'm a total quilting novice, I ended up with 3 coordinating fat quarter bundles and figured that I can go from there. 

Now that I want to make something a little more complex in design, I'll readily admit that I am ridiculously overwhelmed as to where to begin with the quilting thing!  It's like a chicken and egg to me - do you decide on the quilting pattern then buy the fabric, or the other way around?  How much fabric are you supposed to buy if you don't know what you're going to do with it yet?  Having already purchased fabric intended to go together, how easy is it to modify an existing pattern to make those fabrics work?  The list of questions goes on and on!

Having spent some time at lunch today looking for quilt pattern ideas, I have found a couple ideas that I think will work, although doing all the math based on how many cuts for each fat quarter, and what other fabric supplies I need just might be doing my head in!  I also think that I want to make all of these designs by Jinny Beyer.  For now, I guess I'll keep doodling and calculating until I come up with something that makes sense.  If I get it right, I suspect it'll be pretty though!

So, any experts out there that have tips to share?