Advice for a god-awful GM., I'm referring to myself. Options

[SpasticTeapot]

To cut to the quick, I'm a god-awful GM. My player are all new to RPG's, and after numerous "false starts" where we got fed up after two adventures, I'm giving it another shot.
Does anyone have tips for maintaining a player's interest? Often, my players get bored and walk off. (I told you I'm a bad GM.)
Also, although I'll be using SR4 rules, I'm going to start the campaign in late 2070. After a few "intro" runs, I'm going to throw the PC's into this succession of runs/campaigns, starting in 2071. At this time, I'm going to have someone relatively powerful run for president, possibly a dragon.

1. "Two Solitudes", from Shadows of the Underworld.
In this adventure, the PC's have to track down the son of some sararimen in San Fran. However, the son is homosexual, and to avoid being forced out of college and into a slum, had been keeping it a secret. A Saeder-Krupp spy then blackmailed him, but in order to avoid having to give over the information, the son decided to conjure a very powerful elemental/spirit. Not surprisingly, he knocked himself unconcious, but instead of running rampant as free fire elementals are like to do, he instead became a free spirit. The two fell in love (the free spirit is decidedly male, no "flaming" puns intended) and ran off. I intend to run this after the PCs have gained a rep for being moderately decent people, through doing runs such as as "Supermarket Shuffle".

2. "C.O.D", from Shadows of the Underworld.
In this run, the PC's are given a Dragon's egg... and are not told what it is. The dragon, having been knocked unconcious, is expected to be very angry and destroy a great deal of property in it's effort to get the egg back from the PC's, therby discrediting the decidedly pro-metahuman candidate. Considering my players, I can safely say that they'll give the egg to the dragon. However, seeing how Masaru is now a GD, I'll have to use a somewhat weaker dragon, with weak being a relative term.

3. "Excelsior", from Shadows of the Underworld.
After at least one or two "ordinary" runs, the PC's get a call from the chief publicist for liberal candidate X. (The same one that was to be discredited in the first one.) During the meeting in the empire state building, they're asked if they can ferret out threats at Liberal Candidate X's rally. (someone's theatened to put a bomb in there, and the PC's will need to get it out.) However, during the course of the meal, a bunch of crazies who think that Candidate X is going to save the world or something of that sort plants bombs, and the PC's get to be heroes if they don't screw up or run away.
As an added bonus, if they don't blow up the publicist, they get the job at the rally. Seeing as how it's essentially an easier version of Excelsior in most respects, they should breeze through.

4. "Harlequin's Back".
Seeing as how the PC's now have a rep for doing good stuff, Harley hires them. I still need to get a copy of HB, but I figure that it will take a few months for the PCs to get to this adventure anyway. At this point, we decide wether we simply continue with a normal SR game, start a horror-hunting campaign, or simply retire the PCs.

I would like to have an adventure between 3 and 4 that starts to introduce them to the power players, and has a lot of combat. "Imago" would work nicely, except for the fact that ghosts in the machine are not all that rare after the Crash. I was thinking one of the Bug Spirit runs might work nicely. (Queen Euphoria, perhaps?)