Lots of good advice already in this thread, and since I just spent the weekend helping a friend get used to shooting his new 908, I'll add a few ideas.

First, coming from 1911 semi-auto's, the 3913 trigger is going to take some practice to get right. I've found 1911's to be the easiest pistols to shoot accurately, but they kind of spoil you for a TDA trigger like this. To start, I would recommend doing a lot of dry-fire practice with your 3913's DA trigger pull. Think of it as building muscle strength and memory, and don't go overly slow to begin with or get caught up on you're sight picture or being perfect. Get your hand used to the trigger pull and weight, with a secondary goal of trying to keep the gun steady while you're doing this. After the gun feels more natural in hand from this practice, slow the pull down and concentrate on more finesse with a smooth trigger break and steady front sight.

Secondly, I prefer to place the pad (or middle) of the end of the finger on the trigger when shooting. This seems to me to be the best way to mitigate shooting to the left.

Lastly, leaning forward with your stance, locking the elbows out, and keeping a firm (but not a shaky death grip) on the gun while firing will give you a good base and hopefully help with the shots 'dipping.'

I'm sure that you already have heard some of this advice, but basically what I'm stressing is doing lots of dry-fire practice off the range to get yourself used to this pistol. It pays huge dividends at the range (and can save lots of money too).

Best of luck with you're 3913!