I mentioned once before that I have a habit, when shooting revolvers, that does not meet current standards: I generally, when it's pointing downrange, have my finger inside the trigger guard. Off the trigger, but in the guard. It's the way I was taught, and I generally still do it that way. Various people have informed me I'm a bad boy for this, but I'm not the only one.
From what I understand the 'finger straight along the frame' started because that way it's real easy for a rangemaster to see that the trigger isn't being molested before time. Well and good, and generally a good idea.
Semi-autos? I didn't fire a semi-auto handgun till sometime in my 20's, and I always tended to keep my finger out of the guard; safety or not, knowing that trigger didn't have the same 'pull a ways against firm pressure' I got from a revolver made my shy of getting near it until ready to pull it. So I was doing the 'finger mostly straight' position before I ever heard someone speak of it that I recall. But on revolvers(double-action, larger trigger guard) I still tend to have my finger inside the guard.
Also: I was once chewed on by someone for 'not having my finger straight'; it was outside the guard, nowhere near the bangswitch, but it not being absolutely straight or- preferably-up high on the frame wasn't good enough for him. Screw that, I'm not worried about fitting the 'perfect picture of safety' mold. And yes, I did tell him that was just too bad.
Something else that comes around occasionally is point-shooting. Most come down on the 'Use the sights unless you're in contact range', with some saying it's great. Again, when I was taught to use handguns it was pretty much as Bill Jordan showed it in his book(earlier post here): point-shooting up close(I was taught get that off-hand on the pistol as soon as possible, one-handed was for if you could not use that other hand or you were in contact range), using the sights if time/distance to do so. I think much argument involves people trying to hold the piece a hip-level even for targets ten to twenty feet away, which I think is a big mistake. I prefer to have it far enough forward that even if it's not in line between my eyes and the target, the pistol is in my field of vision, and with some practice you can keep shots well within minute-of-goblin, even when moving around. I consider it one more tool in the box; being able to shoot this way in bad light/up close situations is a good thing, in no way a substitute for using sights, just a useful skill 'just in case'. Not every gun has a laser or night sights, and knowing that feel of 'you're on target' even when you can't see the sights, or can't see them well, seems a very handy thing.