LOL I always do my quilts this way!!!! I've done a couple by pattern, and end up cursing up a storm!
The first thing I would do is simply sketch what you want. Then break it down into blocks, and put those blocks on the graph paper.
I'd buy bigger squared graph paper and have each square represent an inch .... and you could take it from there!
I do most of mine in PowerPoint LOL
Have fun!