From the infamous "Dark Dungeons," by Jack Chick
There are many, many forces arrayed against an RPG session that must be overcome in order for you have a great time. Countless distractions that can make us forget why we are at the tabletop to begin with. It's important that both the DM and the players recognize these distractions and deal with them accordingly.
Most can be overcome with good communication, scheduling, and a promise from all players to keep their commitments. Even so, these top five can become ongoing distractions if not dealt with.
In my experience, you've got the "gamer stigma" working against you. The "closet gamers" (how I dislike that term) out there may like your game, but are afraid that the might be made fun of for ditching their non-gamer friends to play a wizard.
Overcome this by having strict scheduling and a great game. If you're a DM and your players are sports fans, listen for cues for when the next big game might be coming up.
Don't schedule a game for Super Bowl Sunday. Like I did. Once.
I've lumped these together, though they are different in many respects. There really isn't much one can do when work calls and says, "Guess what? We've rescheduled your shift!" or you're salaried in the corporate world and just some tasks overflow into your fun time, or your just beat from a long work week. Commutes can also eat up lots of time.
School is another matter. Common sense dictates to get your homework done. When I first came to college, somebody said you were supposed to spend at least two to three hours in study for every hour spent in the classroom. To me that sounded crazy... but now, looking back perhaps I should have been paying more attention.
How many times going into an RPG session was I nervous about getting an assignment done for the next day? That nervous energy, I'm certain, sapped from the play experience. How many times have you done this?
Again, the best advice is to get your work done. If you have to work for the weekend, then do so. Don't let work/school time interfere with your fun at game time.
#3. Other games and gamers
If you're fortunate to be able to play in the privacy of your own home, this shouldn't be too much of an issue. Just turn the TV off, perhaps even disconnect your Internet connection and ban computer and cellphone use (see #2), hide your board games, ban edition war speak and talking religion and politics.
However, if you're running a game in public or semi-public place, such as at a college campus gaming club, or gaming store, you'll full on into other games and gamers distracting your players. At the very least there'll be the noise factor, or lurkers stopping by. At worst, you'll end up in a feud with the CCG gamers (usually a tournament), wargamers, and other RPG groups who'll want to use the space you've occupied.
There's really no easy way to circumvent these problems if you're playing in a public forum.
The best way is for as many players in your group as possible to arrive early and stake a claim--two players at the very least. If you can, find the most quietest and out of the way place.
If you don't like noise, try avoiding CCG nights--especially Pokemon or Yu-gi-oh, which attract a large number of restless children.
#2. The Wonders of Technology
Sometimes I wish cellphones/smart phones were never invented. Sometimes I wish we could go back to the 1990s when laptops hadn't become so prevalent.
I don't have much else to say about this one, we all know how distracting the wonders of technology can be at the gaming table. My only advice is: UNPLUG.
#1. Significant Others
In the United States, anyway, there's this weird unspoken assumption that couples are supposed to do just about everything together. I have no idea where this comes from--marketing? The media? the TV-show Friends?
On top of that, guys are supposed to feel guilty for not spending time with their wives or girlfriends. But if they spend too much time, then they're smothering. Yet if they don't spend enough time, then something might be wrong in the relationship.
(What's the female perspective on this? No really, enlighten me.)
This bogus assumption can disrupt your gaming session, if it hasn't already. A significant other who becomes a gamer can be wonderful thing, but a jealous partner can cause unneeded drama. In the very least one of your gaming buddies probably won't show up as much anymore.
All I else I can say is treat each situation differently, but try to win the significant other over to your side if possible. Proper scheduling helps...
...as does getting older, and more mature (I think).