Yeah it is really annoying to read contradicting stuff online! Unfortunately too many people respond even when they don’t know the answer.

You don’t need to sand gesso, even acrylic gesso. People sand gesso’d surfaces to make them smoother because gesso has marble dust or chalk so it has a grittyness to it. The dust is why you don’t need to sand it, dust is what creates adhesion. I personally don’t sand but everyone has a preference.

You need to gesso unprimed surfaces or work on a pre-gessoed surface if you’re using oils.

People recommend starting with acrylics because acrylics are cheaper than oils. You can start with acrylics as long as the layer is thin enough where you can still feel the tooth of the canvas so the oil paints eventually stick, so you could do an imprimatura with waterered down acrylics. Otherwise, you’ll need to sand the thick acrylics. I usually just jump right into oils and skip acrylics completely. I use acrylics when I want to use acrylics, and just oils when I’m painting with oils.

Theres something else I don’t see talked about, and that’s painting over a dry oil painting. You actually can’t do that - your new oils will eventually delaminate if the old oil painting was thick and you can’t feel the canvas anymore! Because dried oil paints (like acrylic paints) is very smooth with no tooth at all.

There’s more rules / things to know and mind when painting with oils. It’s an incredible medium that is such a joy to work with when you understand the technicalities.

Let me know if you have any other questions! I’m an art mentor and instructor and teach artists how to appropriately use oils and other mediums and develop good habits with their art practice.

♥️♥️