Sub ohm vaping makes me cough, too. Here’s my 2 cents:

1st choice: Tank: Asipre Nautilus tank with 1.8 ohm coils. Suggest the original version tank or the 5ml. Hard to notice when tank is almost dry with newest version and only holds 2ml. Mod: Eleaf iStick Power 80watt. Set voltage at 4.2 max to start and lock it in at that voltage for her. 50/50 juice or higher PG for satisfying hit. Around 15mg nic to start for PAD smoker. The mod is overkill but a workhorse. The internal 5k mAh batt lasts a week on a charge for mtl low voltage vaping and cost about $35. Any good brand internal batt mod with ability to lock in voltage/watts is fine. This one has nice feel in girl hands. Buy from a legit shop. Ebay coils, mods and tanks are likely fake and the coils deliver nasty