A general rules I follow most of the time is that the low frequency sounds are most centered and the higher the frequency gets the wider they get placed in the stereo field. So elements like the Bass are usually mono right in the middle and sounds like high hats I often place more to the side.
Not a rule you have to follow but it can help in keeping things clean.
I didn't read the OP that way I guess. And I tried not to sound snarky, really I did.
I I usually slightly pan extra percussion and hats as well as synth sounds and instruments while thinking about the frequency spectrum to avoid things clashing and having to EQ less. I'll even sometimes pan the snare/clap. I usually keep the bass and kick center, usually. And typically with the drum kit I'll pan it so it'll sound like you are facing a drummer and listening to him play...so I pan the crashes and hats accordingly and the snare if I'm panning it.
I usually don't pan more than about 12% either direction if I'm using panning as a mixing tool.
One "trick" I've been playing with lately is having an aux send with a delay into reverb or a reverb into a delay and panning the effects pretty hard in opposite directions...so it sounds like the delay/echo moves into the reverb on the other side...if that makes sense. Gives a surreal sense of space to the mix.
I used to pan all sorts of drum hits hard left and hard right because I thiught it sounded like autechre. Then, one day a while back, I realized it sounded like crap and nothing at all like autechre so I stopped doing it. Some times I still like the occasional panned hit but now I don't pass 35%. Also if I'm going to pan a hit in that way I try and give it some purpose by thinking what comes before or after it.
I try and figure that out with any process these days actually. Finding the proper place for something to sit in time is just as important as finding where it sits in the mix. By in time, as I said above, I mean in the context of what comes before and after it. If its not doing something for a reason, get it out of there or move it.
Also +1 on panning the drums a tad for space. Usually I do that manually or with some sort of widening tool like abletons utiliy plug.
Generally, anything of any real importance (the backbone of the track, if you like) is centred. Talking kick, snares, off-beat high-hat, synths, bass etc. I then add on some panned hits to add space in the percussion and pan various smaller elements that add extra 'feel' to the music, and widen the stereo image.
60s-70s style panning can be fun sometimes. A song I mixed for an indie/punk band had a coda with a cool bassline and lots of action on the floor tom. I wanted both to sound really full and big, so I panned them on opposite sides about 50-60%. Panning something important can be a great and surprising thing.
Yeah I only really pan hard left or right when I am going for a Haas effect to make something sound wider. To do this you double the instrument you want to sound wide, pan one all the way left the other all the way to the right and then you delay one track by 10-20ms.
When I'm panning, I tend to consider the placement of machines/instruments/percussion on a "stage" setting, just as one would pan an orchestral piece to emulate the effect of an actual orchestra in front of you. Sometimes I will also do fun techniques like randomize panning every beat (not hard panning mind you, maybe a limit of 50% one way and 50% the other) on a track with just hats, so the hats kind of come at you from all directions like a swarm of bees. Also, sometimes I will pan things that sound originally too far left or right to be more centered, because hard panning can tend to onset anxiety.
I play with panning mostly with my percussion like people have been saying. Sometimes if I want a really wide sounding snare/clap, I'll throw a sample hard left and a slightly different sounding one hard right (being careful of phase cancellation ) and my ears usually accept the illusion of width.