This is probably covered here somewhere as advice for new people coming on the scene, and hey, I probably covered it myself in years past here.
If you are new to GMRS and buying a couple or more radios to put a group on the air simplex for activities, please consider a good read of the manual and programming, then do a little homework locally, or where you intend to use them, before settling on your "home channel".
I suggest scanning, with no tone set (CSQ) on all channels to see who's using what channel and how strong the signal is, before picking one. It's not a matter of " not getting on someone else's channel", no, you got your license so you are entitled to use all of them too. They are shared channels. What it does for you is allow you to pick the best one for your area so you don't run into same-channel usage, or as much (remember, someone else using a channel is NOT "interference").
Once you find a fairly quiet one, or maybe even an all-quiet one, then you can make it your home channel, and pick a tone/code for squelch if you like. I have, in the past, even setup a receiver at a good site, and used a vox recorder or a program called scan-rec which is the same, just in software so you can use a PC, and let it run for weeks to see what's going on.
By monitoring in open squelch, you can hear it all. If you program a tone too soon, you will only, possibly see a busy light, if you are looking, and not know why, at the same time you may have trouble communicating because it's a busy channel and you didn't know it. Searching the database here, and avoiding the existing repeater channels is a good idea too, that way you can steer your activity to a lesser used channel. Of course if you will be using a repeater, this really only applies if you want a secondary go to channel everyone knows to use, a designated backup, so to speak.
All of this is known as self coordination.
I bring it up, mostly because you can sure save yourself a lot of headache and be much happier with the performance of the radios when you are not a victim of so much co-channel activity.
I also mention all of this because for years, I have heard people get new equipment and start using it...on channel 1, and sometimes code/tone 1. This does no one any good unless you are the only guy with that idea. Ever.
Happy communicating!