If you will have under $7M in your estate, the slightest is literally nothing. You will not owe a penny of federal estate tax.

If you have over $7M in your estate, it's worth consulting an estate planner, but the basics look like gifting and establishing trusts while you are alive (and ideally while the exclusion amounts are high).

The current exclusion is $13.61M per person, or 2x that per couple and set to drop down to $5.6M in 2017 dollars on January 1, 2026.

If there's a chance that you'll have over $7M and die in 2026, the slightest is gift some of it now [directly and/or via trusts or 529 plans] while the estate tax exclusion is still $13.61M and file form 709.