First of all, you have to know that modern mobile operating systems like iOS and Android handle the GPS, the app just gets the location data from the device. So all apps are created equal in terms of GPS accuray and there is no way to improve it inside the app. Only you can do a little bit to improve the accuracy.
There are apps for monitoring the GPS of the device, they show you the number of visible satellites so you will be able to find a place where the GPS signal is better. These apps are not able to boost the GPS, they just give you information about the state of it. This looks professional, I suggest you donwload one of them and play with it, but you don't really need this for finding a place with better signal: just find a place where you can see the sky.
Yes, the most important thing is to see the sky. Do not cover the device while you are waiting for a GPS fix, and never expect good GPS signal inside buildings.
If you have network signal then AGPS can work. AGPS helps your device to find the first fix faster, because it will tell it where the satellites currently are so the location calculation will be easier. Having the first fix is always the hardest thing.
So the second thing you can do is finding a location where you have data connection.
Note that at home you can get good accuracy indoors because your device uses wifi positioning, not the GPS. But this works only where a lot of wifi stations are near to you so definitely not on the airsoft site.
This means that you can track your location with your smartphone only outdoors.
Lastly, you have to know something about BattleTac: There is a setting: 'Position report interval' which you can change to a higher value (e.g.: 5 minutes) to save battery time, but if you do it, you may get worse GPS performance. This is because 5 mins pause is too much for the GPS, it will 'cold start' every time which is harder as I have said. So if your GPS signal is bad then I suggest you using the default value of this settings.