The advice I have on the tank tips is to fill them 3/4 full, wipe them off, keep them tip down while inserting into the nozzle of the eGo-C which you hold upside down. Be sure there is no bubble at the neck of the tank filler hole or any extra fluid before inserting, use a paper clip to pierce any bubble before inserting and then wipe the filler hole end again.
If you are getting a burning taste, draw on the tip without firing a couple times, then draw a few times while firing but don't inhale to clear the burned taste.
If it still tastes burned, change your atomizer, start fresh using the method above and take the burned atomizer and drunk it in boiling water twice, changing the water between dunkings, dab extra water off, let dry overnight or dry with a blow dryer. Once dry, put a tiny dab of juice on the wick tip, (really tiny), wipe off the atomizer and reinsert into the battery chamber, (being sure to wipe the battery connection spot if it had any fluid on it).
If you are having leaks around the tank top filler hole, where it connects around the edge to the tip, replace it with a new tip. If you are having leaks around the threads where the atomizer is housed, you need to open it up and carefully wipe it out.
This is what I learned and have done, now I have no problems. Remember to draw slow and even the first draw, then you can puff a bit.
This is all I know so far, had the same problems you describe and am now happily puffing away....