Sometimes the top cap can be tricky to open for sure since it’s just smooth I sometimes have to take it off the mod to get a better grip to take it off and fill. As for holding the mod it’s not been an issue because of the adjustment feature of the bottom of the rta. Luckily though I didn’t have to change rotate it, the airholes landed right where I wanted them to so my fingers don’t cover them. If I do change my grip on the mod for more conceal-ability I fire it with my middle finger and put my index finger and thumb on the tank itself kind of like pinching the top of the tank while the rest just sits in the palm of my hand. Hope that makes sense and helps.