For prob blur, I try for 250 or less. 125 might be needed for slower props (e.g. old radials). I have shot under 125, but it requires a bit of luck depending on the speed of the plane (I have done a fair amount at Reno, so some have been very fast!). Using shutter priority (e,g, to sport mode), is likely the best option. For full prop blur (full disk) you will need to go very low).
Steady tracking is necessary. Hold the camera with your right arm as closed to you chest (e.g. not sticking out) and your left had as far forward as possible (braced to your chest also if possible). Follow the plane (track) and get a steady rate of rotation before you shoot. Twist at you waist ONLY, this will produce as smooth a rotation as possible.
The best setup I found for steady tracking was using a monopod, with a remote trigger taped to it if possible. Don't put the monopod on the ground, bend it and tuck it under you right armpit and use it like a rifle stock. They used to (still do?) make rifle stock type attachments for this.
For fast planes and tricky blur shots, shooting a bust (if you can) of three or more shots can be useful, at least one will likely be blurred properly. I does add to the editing of course. In these cases it is nice to edit out the bad ones as soon as practical.
Be wary of autofocus and auto exposure for mid-long shots, they can sometimes be tricky. Using a pinpoint exposure setting and non continuous is useful. Setting it on the plane before you shoot or maybe a ground object if the sky is too bright is useful. Autofocus can be tricky at mid long also, if you are having issues, consider disabling it and going manual if needed (you get a good range of focus if you lense is not to giant).
Keeps aperture as small as possible for maximum depth of field. Playing with this of course can create some interesting effects.
Another nice tip (that I tend to forget) is take a banner shot at the start of each day or significant division in what you are shooting. E.g. shoot a pic of the entrance as you walk in each day, and maybe some random poster / banner when you want to note a time. It will make it a bit easier to sift through the photos. A bit more useful when you are changing locations (e.g. road trip).
Most all of my Reno stuff is film, so I don't have examples. I also used to have a very long lense (600) so I was getting much closer shots. Here are some examples that might help:
Should be some GREAT opportunities there (I was there years ago, actually flew in and slept under the wing of a 172). Don't forget to be ready for the "golden hours" near sunset, and especially near sunrise (if you are there of course).
This one is 125 (lower engine speed):
this one is 320:
This is 500. As you can see, a bit fast, and I still didn't get a good focus (this was Chino BTW, another very good show)