Definitely a 510 pin is good to start off. The ones where it's direct contact to the battery positive are quasi-hybrid.OK, I found the thread titled "A beginner's guide to your first mechanical mod." Seems that a 510 center pin is a good safety feature. Didn't know about the extended vs. non extended pins on the atomizer. Looks like some more research is needed before just buying something. The gory pictures worked! Thanks for the replies.
For a stepping stone, I've really been enjoying the Ehpro Armor Prime. It's a pass through (unregulated) tube mod with a bit of protections (reverse polarity, short circuit,...). Good manufacturing quality, solid. A really nice (to me) side fire button. Two tiny LEDs bracket the button, indicate any problems and change color based on battery voltage. When they change from green to yellow that's 3.6V, a decent spot to swap batteries. fasttech has the newer version, that also fits a 21700 battery.
There's a classic true mech on sale now, too. It uses an 18650, does have a 510 pin (not a hybrid). asMODus Rose Finch Mechanical Mod single 18650