I have a couple things that have worked in the past with my group when we were first learning 4th edition.
1) Read the book a bunch. I try to crack it open and just read a section or two at least once a week. It's very hard to remember it all in one shot, so these little refreshers work really well and I pick up something new every time, even from sections I've read multiple times. Just don't try to read it all in one sitting, that's hard for anyone without really good memory skills to do.
2) If a rules question comes up in the middle of play, make a decision that makes sense and then have a player who's less engaged look it up for next time. Works well, keeps combat flowing while the Hacker/Face/etc not doing much can feel engaged. Also helps players learn rules too.
3) You can add rules as you go. You don't have to start out using everything, not every rule is crucial to use from the get go. I let my players know that I'm not using everything and will be staggering in things, like Matrix Grids, Noise, Background Count, some environmental modifiers like weather and wind, etc. When the group feels like they have a handle on things add something in that you weren't using before.
4) House rules should either make the game easier, or enhance play enough to justify the complication.
5) I make sure each player has read the rules section relevant to their character at the very least. Street Sams should read the Combat rules, Faces should read up on Social Skills, Mages on magic, and so on. They don't need to read everything, but they should at least go through the sections of the book that they'll use on a regular basis. Cuts down on a lot of looking things up. Seems like common sense but you might be surprised at just how many players don't do this. Check to see if they have and ask them to if they haven't.
6) Sometimes it's ok to break the rules as the GM for plot purposes. Just don't turn it into a habit, the players want to play in a world where they can reasonably expect cause and effect to work the way it should.
7) Planning ahead is great, but don't get too detail oriented in planning. Players tend to go in different directions then what you might expect. You plans should be flushed out enough to have a good story, but loose enough that if the players do something completely unexpected you don't dump 5 pages of work in the trash. I tend to focus on making NPCs and their goals, locations, and a very loose idea of objectives and possible complications. The good thing about this is even if the players do something and this info isn't used, NPCs and locations are still useful and can be used again in a different run or situation. Modular locations are great too: for instance if you come up with a small stretch of sewers, that can be used in the Orc Underground, as a way into a secure Megacorp site, as a emergency safehouse that a contact knows about, or a paracritter cave with just a few minor changes in each case.
Anyhow, those worked well for us. Maybe it can for you too.
