Using an e-cigarette is not exactly like a tobacco cigarette. Vapor is different from smoke. Remember, you are no longer smoking....but "
vaping".
The majority of nicotine in vapor is absorbed in the throat, mouth, and nasal passages...not in the lungs. Different size molecules..vapor and smoke. Therefore, its not entirely necessary to inhale the vapor into the lungs for nicotine absorbtion...it can be used like a cigar or pipe smoker uses tobacco by not inhaling.
However, most of us desire the complete cigarette experience of inhaling into the lungs. Proper technique would be to imagine sucking on a straw in a milkshake. Draw in in a slow, gentle, longer draw. Use your cheek muscles to draw a mouthful of vapor into your mouth, and hold it there for a second or two. This allows for maximum absorbtion of the nicotine, and allows for the vapor to cool a bit.
Then inhale a small amount (at least initially) of vapor into your lungs. Exhale through both your mouth and nose. Your sense of smell assists your sense of taste to perceive flavors. Remember when you have a cold and your nose is congested, and you can't taste your food? This shows how important sense of smell is to the sense of taste.
When you first began smoking tobacco and inhaling smoke, I'm certain that you must have coughed. It's a natural response of the body. The same holds true with vapor. It will take a short time to adapt to vapor like you did with cigarette smoke.
May I ask how many cigarettes you smoked daily, and what nicotine strength e-liquid you have? It's certainly possible that the nicotine concentration in your e-liquid is too high for your needs.