Whatever radio you're using for DF needs to have a good signal strength meter. That has to be coupled to a directional antennal. I tried a Baofeng UV-5X3 and even though it has a simple signal strength meter, it was pretty much useless for DF with a Yagi. I was, however, able to find my rocket my using my body as a radio shield and walking towards the null.
To do that, you're putting a giant bag of water (your body) in between the radio and the Telemini. Turn the squelch off, then turn 30-45deg at a time to listen to the Telemini's beep. If you're holding the radio flush with your chest, keep turning until you don't hear the Telemini. You're then facing away from the Telemini...turn around and walk that way. If you get close enough that you always hear a signal, you can remove the antenna and keep doing it (just don't hit the transmit button without an antenna).
You already have a Teledongle though, right? That reports signal strength. You should be able to hook a directional antenna up to it, then slowly point the antenna in different directions, then walk towards the peak. If you have an Android device, you can hook up your Teledongle to it and use the AltosDroid app to see the signal strength (RSSI).
You wont' get a direction or distance from your computer screen though. There are lots of videos on YouTube and websites about ham fox hunting. There are lots of ideas out there.
One gotcha I've seen is you may get radio reflections off of nearby mountains, fences or other RF reflective things. Don't get spoofed by that.