So in the last session, I really did accept my limitations and used 3 strategies to make up for my weaknesses.
First, I relied more on the player's familiarity with the rules to help me runs things correctly. Here is an example. I had three rangers tracking the party (the party knew about this) and came up with a track DC that seemed too low so I asked the players to look at the rules and tell me what DC they would assign to tracking them. This openness to hearing from them seemed to work very well. It allowed players to correct my mistakes without generating a me v. them tone at the table.
Second, I copied a d20srd monster entry into my e-notes, file, I also copied the description of the type, special abilities, etc. It made for a longer entry but I didn't miss as many things as I ran the monsters.
Third, I went more slowly. Instead of really pushing to make the combat faster, I waited, considered, and looked things up more often.
The irony is that as successful as these strategies were in reducing my rules mistakes, one of my players was much less satisfied about the session though not for this reason.
He was frustrated because I had the PCs were brought to meet a general under armed guard (loss of control and heavy handed direction of his character frustrates him to high heaven). I did this because I asked what was most likely given that the PCs approached at night, fully armed, in the middle of a war zone, and the military was fighting small guerrilla groups of 4-5. *sigh* so much for my most frequent GM algorithm, "What makes sense here?" It got to the point where he accused me of railroading the party and we had to pause the play for about an hour while I tried to figure out which parts of the GM curtain I could pull back without revealing too much.
The accusation of railroading was particularly hard for me because I agreed to run this campaign on modules up to level 6 when the group didn't have a GM. I said explicitly that the campaign would be on the rails because I didn't have time to plan more than that. Once the player's reached level 6 I said I have a little more time so I stopped running the game on a strictly linear path but that I am also trying to bring the story to a close so I sent out a long email about how the game would be run on converging plot lines and that they could decide which set of rails they'd like to get on to take them to the finish line. So, in light of my multiple attempts to set up the expectation of some railroading (and asking for patience for it) and granting freedom when I could grant more freedom ("which set of rails would you like to be on to the conclusion of the campaign?") it was a hard accusation to take.
This conflict has placed me back in the question that I've asked several times recently, "Where is the line between loyalty to my friends and trying a different gaming group to try to increase my enjoyment of the little free time I have?" Anyway, long story short, I got him to calm down and give me a little break and everything went better after that.
Now I've got my group planning an assault on a guard tower that they have the layout for. The session slowed to a halt as they entered a more Shadowrun style of planning, reading their abilities, coming up with contingencies, and so forth.
I've made it clear that I'm not sure that I'm ready to run my Psi-Marine campaign with this group. I think my GMing style and the group's needs may not match enough to maximize enjoyment for all involved. I'll keep considering these things as we get closer to the end of this campaign.