A bit of irritation is also really common at first, for everyone.
Prior suggestions are all solid, my only add would be to drink lots of water -- that's one habit I, and many others, had to pick up when we first started. I keep a water bottle at my desk, now it's pretty much unconscious.
I'd also agree that your nic is perhaps too low in the eliquid. An 18 mg/ml strength is pretty typical for a "lights" smoker, with most "full flavor" smokers using 24 mg/ml; some people are up or down one level from those values, but they're pretty typical. 8 mg/ml might just not be giving you enough nicotine.
Also, vaping varies from smoking in that it doesn't include any freebase nicotine (faster acting), carbon monoxide (part of the "rush" if you take a sharp drag on a cig), or MAOIs (things that extend the effective duration of the dopamine that nic releases in the brain). You may well find yourself needing/wanting to vape more frequently than you would have smoked, due to the MAOI aspect.