Group all same type of plants in same area? For example Amazon Swords on the back left and right corner, then some other type sword in the middle and the left of the tank some other type of sword, or mix all swords up, like one type, then other and so on across the back?
I think its a stylistic choice. There are no rules. You will achieve different results for each choice of methodology. It all depends on how you envision your final result.
I think whatever method you choose, you should consider the eventual size of the plants you are working with. I would also consider the speed at which they grow, and shapes they are capable of making. This would help you to gauge where they should be placed. For example, you more than likely wouldn't want an amazon sword in the foreground because they can become very tall. But my point is that this is your choice. You can put it in the foreground if you want. Always research and it will be more intuitive.
For guidance I would suggest browsing pictures of planted tanks and using them as reference guides. You can see how different people creatively group and use plants.