What is the best way to mount RX antenna on drone?

That is a matter of opinion. I usually have mine on the arm with tie wrap for the support. Usually pointing down. You can check out some of my build logs to see what I mean. These are the things I try to do when mounting. Keep it away from props. Keep it as unobstructed from the carbon as possible. Make sure they don't flop around.

I like the PTFE tube option and it's what I used when I built my 5" (see the photos from step 7 onwards in my original build thread HERE). They make for good aesthetics and keep the antennas up away from the carbon each at a different angle to each other for good signal coverage. Plus being in a tube the antennas are well protected. Some argue that with the antennas inside tubes it degrades the signal strength, but tests have proven any degradation to be negligible and no worse than antennas running the length of a cable tie with heatshrink covering them.

The GEPRC Phantom I have also has the same set up (photos HERE). Something to keep in mind though is that you generally need some kind of 3D printed mount if you are going to use tubes because something needs to house them.

I was thinking to mount it as oscar showed in his website with cable tie and shrinking tube, but this version what Snow showed is pretty sweet looking. I have a friend with 3D printer so maybe I want to ask him for a favor:') Are there any other rules or advices for good antenna mount? oke one is to keep the antenna away from carbon is there anything else to consider?

https://www.banggood.com/10-PCS-iFlight-...rehouse=CN

is this good enough? or i need to buy something like this:

https://www.banggood.com/3pcs-Red-1M-Lon...rehouse=CN

First link is better.