Turn off sensors and do not record video on SD, these can save you a bit more juice...
I'd check alternate landing sites just in case, and brush up on the procedures to be sure you actually shut the drone down should you need to land somewhere and not end up letting it try to RTH itself.
Also agree to being very sure about windspeed and direction not just at ground level but whatever level you are flying at as well. You don't want to turn around at what you think is about half battery and then realize you have a huge headwind.
Lies, I tell ya! All lies. My description above is accurate. Do the smart thing and test it. Fly a wonky path out to 1,000ft, then hit RTH. All of your questions and concerns will be answered.I read somewhere that there were different behaviors for RTH, and that it followed the flight path in reverse back to starting point, which is NOT helpful.
Stay out of wifi conjestion, DON'T use those signal booster things (utter garbage, I'll do a video about them) sports mode is fine though, just nukes battery.
And rth takes straightest path home at rth height, so just make sure that's above any obstructions in your line of site.