I was kind of hoping that some expert would reply after seeing what it is you are striving for. I am not one of those experts, but I will give it my best.
First of all, you will want to group similar plants together, larger ones to the back, smaller to the front. Try not to make the groupings too geometric and vary the areas covered by each species. An interesting layout is to make a rough "U" shape out of one mid sized species of plant, and fill in the back, sides and background with less interesting plants.
There is an area that Takashi Amano calls the "golden section". It is approximately 3/5 across the width of the tank. In this section you will want to put in a centrepiece, be it a nice piece of driftwood, a large stone or perhaps a larger single plant that stands out in colour and shape.
Fill in the foreground with a low height "ground cover" plant and your set.
It might be helpful to draw out on graph paper your imagined layout before you start yanking and replanting.
Like I said, I am no expert, but I hope this helps.
BTW, it might be a good investment to purchase Takashi Amanos' Nature Aquarium World book one. The first 3/4 of the book is pure inspiration, the back section is a good guideline in achieving a more beautiful planted tank.