First BIF

I'm wondering what settings everyone uses for these types of shots. It seems that almost always my BIF shots are oof, focused on bg, or extremely exposed wrong both under and over. This is my first salvageable shot.

Well that looks pretty good against a busy background!

You keeping the shutter speeds up? Even the slightest bit of camera shake or movement is going to show up using your 400.

To my mind your focusing problems are likely due to not managing to keep your AF point on the bird all the time. I use centre point and concentrate on holding it over the same point of the bird as I pan with the approach. Once the bird gets close enough I rattle off a couple of shots. If the AF point slips off the bird you can find that the camera attempts to reacquire focus on whatever now lies under the point (usually the background). That assumes you are in AI servo of course, as you should be.

Other causes of softness could play a part too, too slow a shutter speed, poor panning technique, cheap filter etc.

The exposure issue is because the bird is likely to be a smaller part of the frame than the background, so the meter can be thrown off. You are likely to be shooting against a bright background which can cause underexposure, especially as the underside of the bird is often not lit directly, so is in shade. Simply open up the aperture with either EC or by shooting manual. You can take a meter reading off something in similar light, or check the histogram and image after the first shot and correct accordingly. I can't tell you what exposure settings to use as they will vary according to the lighting and, indeed, the birds colouring.

I tend to shoot BIF in manual mode, centre AF, AI servo