Dielectric grease is great, but of course it doesn't conduct electricity. For the grounds, after cleaning I started applying carbon conductive grease. Effectively there is probably no difference between the two, but it makes me feel better knowing that I am enhancing the ground connection. The downside is that the carbon conductive grease is black and can make a mess if you're not careful. It also has a bunch of chemicals that probably give you and everyone you know cancer immediately
https://www.amazon.com/MG-Chemicals-Carbon-Conductive-Grease/dp/B00SMRNSR0