The most important thing is the grading. Sounds like that is correct already. Is this a new home? If yes, anticipate some settling of the backfill from construction. It is important that you add soil to maintain the grade when that occurs.

I don't recommend plastic. Instead, purchase some landscaping fabric which will prevent weed growth around your plantings while allowing the soil to breathe. You can mulch over the fabric. Otherwise good turf next to the foundation.

It's also important to make sure the downspouts don't dump water right by the foundation. Bury some plastic pipe to move the water out to the yard.