A strong directional antenna would help, but that means that you have to build it yourself, I'm not aware of an off the shelf antenna that has high gain at 315 MHz. So
KerberosSDR.
It's a quad input coherent radio receiver based after the RTL-SDR chips. One such function is it can give direction and strength of signals in a wide area.
And I find this electronic kit antenna works well as long as you pull it out for the appropriate frequency: https://www.nooelec.com/store/ratlsnake-m5.html
I use 4 of these for my KerberosSDR.
With that said, these KerberosSDRs (or any multi-channel coherent SDR solution) are not widespread, are considerably more expensive (6-7x more than a single RTL-SDR), and are only recently available. So my previous point still stands about how armchair hackers can talk about how easy this problem is to solve in theory but they lack the actual equipment to do it.
The KerberosSDR has one very significant disadvantage: the databus is usb2. The theoretical max is 30M samples at 8bit I and Q... And frankly we need much more bandwidth. But for a beginner foray into coherent radio applications, a KerberosSDR for $100~ is crazy worth it.
Now, the older way of doing RDF (I'm a Ham, btw), was to get a handheld receiver capable of listening to the freq in question, highly directional antenna, take measurements and move. Effectively, the human with a receiver is the manual triangulator which can be trained with experience. That was because gear that did triangulation was $$$$$$.
Physically, it's easier to find a UHF beacon (315 MHz is considered ultra high frequency) than it is to find a lower frequency beacon (lots of direction finding contests are done on VHF and HF). The higher frequency means a shorter wavelength and better phase (direction) resolution with a smaller aperture (distance between antennas).
However, many (most) hams don't have equipment that covers 315 MHz. UHF isn't popular because it is shorter range and more expensive equipment (you can build HF equipment with much simpler components, and the design is less complex). Plus, 315 MHz isn't in one of the ham bands, so ham direction finding equipment probably won't be designed for it even if it is UHF.
A wide band SDR would include 315 MHz. While there are many younger hams that enjoy cheap SDRs like the RTL-SDR, many of the older, grumpier hams see it as dangerous and letting undisciplined "hackers" into their hobby. To build a direction finder with an SDR you either need to have an expensive multi-channel SDR (I have a Lime SDR that would work), or you need to construct your own mixer to feed a single channel SDR, or you need to wire up two RTL-SDRs with a coherent clock signal, which puts this out of the range of your "common hacker." Here are two ways you could do this on the cheap: https://www.rtl-sdr.com/building-a-passive-radar-system-with... https://www.rtl-sdr.com/building-a-direction-finding-system-...
So while most armchair HN readers would love to tell you about how easy this is, most people don't have the equipment sitting around to do direction finding on a 315 MHz signal. The best most people could do would be to "wardrive" around the neighborhood and look for where the signal strength peaks, but this will really only narrow it down to a few houses and then you need to start knocking on doors. A good direction finding setup would pinpoint the exact house.
Source: I'm a ham (recently made extra), but no, I won't tell you my callsign to prove it.