All good tips so far, but I would add the tip that I received early on that has never failed me and has allowed me to progress up to dropping in on vert (still cant skate vert for shit, but I CAN drop in).
The "thing" about dropping in that makes it different, and the reason its scarier than rolling up and down the tranny is a matter of momentum and control.
Starting from a cold stop, there is that "dead zone", where momentum has started, but all 4 of our wheels haven't touched down yet, so we have yet to gain "full" control over the board.
We're "going over the falls" and hoping that we smashed our foot down in the right spot. We need to "eliminate" or "minimize" the dead zone". But how?
The key is to SMASH the front wheels down with AUTHORITY. Smash harder than you think you need to. As hard as you can without throwing your balance off.
Try it on flat a couple times. You should be aiming to feel low, centered, and propelling forward (even on flat) with full control. It may feel silly doing it this way, especially on something mellow, but later on, it will translate into generating more speed off the drop in i.e. higher airs and longer grinds. You can always taper back as you see fit, but be ABLE to maintain control at full force.
What ends up happening, is the steeper the drop in, the harder you'll need to smash to get the wheels down, so be accustomed to doing it already. By focusing on the smash, your body will instinctively adapt to whatever angle it's being called to, as long as you don't hesitate.
Once your board is set, "it's eye of the tiger up there", visualizw success, do NOT think. Just SMASH!!!
Remember, you may be on a steeper wall, and your "lizard brain" is trying to stop you, but your BODY has already done this a million times, albeit on something a little less steep. Sprinkle a dash of "fuck it" on top and "COMMIT!! You can do it, Danny"