If it's a new bike or new to you, read through the owner's manual beforehand. If I hadn't glanced through the manual I'd have never known my long term VTX has two drain plugs, instead of the one I'd expected to find.
Gather up everything you'll need before hand, that means tools, drain pans, rags filter and oh yeah, oil. I'd recommend keeping an extra quart on hand for topping off as well.
Oil drains a lot quicker when it's hot, so I like to drain mine at the end of a ride, but be careful, hot oil will give you a burn you won't believe, especially if you drag your hand or arm across a smoking hot exhaust pipe trying to get out of the way.
If you want, there's no harm in letting it drain overnight, but in a practical sense it's as drained out as it's going to be after maybe 10 minutes, especially if it's good and warm. If you're draining it cold, allow at least half an hour.
Use a new drain plug gasket and a dab of anti-seize on the bolt and torque it to the proper specs. Stripping an oil drain plug is no fun, especially if you have to pay someone else to repair the damage.
Smear the oil filter O-ring with a drop or two of oil, it'll help the gasket seat and prevent leaks.
Refill the engine using the manufactures recommended grade and viscosity of oil. Using anything marked "Energy Saving" can cause clutch slippage so read that label and if there's any questions as to the oil's suitably defer to the shop manual.
It's normal for the low oil pressure light to remain on for a few seconds after an oil change. It takes some time for the oil to make its way through the engine and turn out the light. If the light doesn't go out shortly after the engine starts a reasonable amount of time is 10 to 15 seconds, stop the engine and investigate, I have seen cases where guys forgot to put the oil back in. Let the engine idle for a few minutes, check for leaks and then shut the engine off.
Let the bike sit for five minutes and then check and top off the oil as needed.
Lastly, dispose of the waste oil and filter responsibly, preferably by taking it to your local recycling center. In some instances, dealerships and auto parts stores will accept the waste oil, especially if you bought the new stuff there, but that's not as common as it used to be.