In general, though, follow spot is a psychomotor skill; you just gotta do it, a lot. Warn your director and LD, and then, during warmups, q2q, and whereever else they'll let you, just follow people. The more you do it, the easier walkon-pickups will be. And already-on-stage ones, too, I guess.
Keep your hands as far apart as possible and use your whole body to steer, to the extent the light will let you. I personally always wear gloves, so I'm less worried about burns, from older spots.
And expect to have to warm up and get in the groove, every single time.
[ My record is 28 lavs on a Beauty and the Beast show... ]
Also (I know this probably isn't feasible for you) but these things are absolutely great for spotlights. A roadhouse near where I live has two of them and I just had our department chair buy four for our spots here at school. Makes any pick-up 98% perfect (accounting for some human error, of course).