Got anything written yet?
I usually start in pretty much the same way as I would a short story, and if it grows from there, I tend to feel pretty good about it.
I'm not sure what's on the Wizards site, but your game will depend primarily on your personal style, both in writing and pace of playing.
Sadly, I'm pretty sure I can tell you more of what not to do than what you should do. You know, stuff like, don't let 'em run over your plot with their agenda. On the other hand, don't railroad them into the plot you have.
. . .
Well, let me rephrase that last bit. Don't VISIBLY railroad your players into your plotline. Hide your rampant railroading (ALL Game Masters railroad, including those who don't prep their game ahead of time. The best ones hide it in what the characters want to do anyway). I know that will seem really freaking difficult at first, but it'll get easier later on. One of the best ways to sneak your rail past the players without them noticing is to put the plot in their path, but not squarely so.
Suppose the character/s a detective, you can have someone hire him/them, but not every character is so obviously open to that type of path. I've had players with every occupation from anthropologist to mercenary to stripper (And that doesn't count those I played myself (ask me about my linguistics professor ne Godslayer sometime)).
The anthropologist is easy; just give him an artifact or strange culture or bizarre ancient gods to investigate and off he goes. Strippers are harder in some ways, but a close focus on what each character cares about will give you the path to their desires, motivations, and path into your plotline.
A stripper might just care about her money or might have a child to care for, but instead lets suppose for a moment that she's motivated by revenge against a former boyfriend. Should your plot directly involve the boyfriend? Probably not. You look surprised. Have the plot only touch on her situation with the boyfriend (perhaps someone who knows both of them) or just follow similar themes to her reasons for exacting vengeance. I suggest low-key versus obviating what's going on, but keep in mind that low-key doesn't mean invisible either.
I recommend that you read. . . a lot before you begin game sessions. I'm pretty sure that others can offer equal reading lists to mine, but there are some things I recommend you avoid pulling from.
1) Any book published by WOTC. But I'm going to surprise some folks by saying that I'm not taking issue with the quality of WOTC's fiction (which I'm not at all keen on). No, this is about the fact that if you're playing D&D, then all your players will have read those same books. Thus, they'll see right through the plot or whatever device you pull out.
I was in a Star Wars game one evening where we were smugglers hired by the Rebellion to mount a rescue of prisoners from an Imperial prison colony. I was cool with it until later on I was home flipping channels on tv and discovered that the entire plot, including the major villain down to her appearance had come from an episode of Xena. It didn't make me mad, so much as tinged the nifty game session with my disappointment.
2) Read the classics.
Don't stick too close to fantasy. For example, ever read the Myth series of books by Robert Aspirin? The first 5 or so are lifted almost directly from Bob Hope road movies. He says so in his Forward (or perhaps it's an Afterward, I forget). What makes them good is that even knowing that, I couldn't really tell.
3) Keep your eye on the plot.
When you're reading (or watching) those classics, watch what the writer does with the plotline and how it interacts with the characters. A lot of professional literary writers want to get rid of plots almost entirely, but I think that's a big mistake. The plot isn't just what the writer/GM decides is happening today, it's what the characters go after, where their choices naturally lead. As your players progress in experience, hopefully they'll see character driven plots as worthwhile, but of course, you'll want to provide a starting point for all that.
If you haven't tried Order of the Stick, I heartily recommend it.
4) Let your characters' choices eventually take the plot off your hands. Not totally - by which I mean bad stuff should happen to them because the antagonists make choices too, but let their choices have consequences.
I had an engineer character in a Delta Green game whose poor choice of words led to almost the entire team killing each other (I think 2 of them survived).
I don't think I ever laughed so hard in my life.
The night I joined my first big (15 players at the time) Shadowrun game, one of the characters had a bounty on his head that I knew nothing about. Well, half the group decided that they wanted that bounty, and that they didn't want to share it or have anyone standing in their way.
Half the group died that night on a bodyguarding gig, and we never did see the bad guys. Oddly nuff, I shot the bountied character and decided to claim his Blitzen as mine. Well. . . BOOM, and I made up a new character.
Man, I walked away from that game grinning my head off.
Well, I've jabbered enough, seeya!
(PS I know that none of the occupations I mentioned are in D&D. Yes, I did that on purpose.)