One way you can pan the instrument is to imagine you're the audience, sitting at the center seat, looking up on the stage where your instruments are placed. There would be many possibilities to experiment with panning. Normally I would set the panning from 10 to 2 o'clock range, but that is just me.
As for reverb, you may want to sent all the instrument to a bus and insert just an instant of the reverb effect if the reverb setting is the same.
Again, this is never fixed, for example, I might be mixing a guitar and it's a little dry, so I may add reverb / delay just a little bit. I may further have these options :
- leave it as it is (other instrument may go to a bus reverb, but not the guitar).
- let the guitar join into the bus reverb.
Experiment and get the sound to your liking.