Inconsistent hits has been my biggest problem too

I'm still working on it - I now use nothing but liquid, and I just add 0.1ml to the cart, plus a little bit straight onto the atomiser to wet it. It doesn't really taste of anything for the first couple of tokes, but then it usually gets going pretty well. After that I mostly keep the e-cig vertical with the light end pointing down, so as to encourage the liquid to run down onto the atomiser. I reckon a lot of my trouble was that the liquid in the "mouth" end of the cart wasn't getting hot, being too far away from the heater. If I get a weak toke, I try giving the e-cig a quick shake (like you would with an old-fashioned thermometer), just to get the liquid onto the atomiser where it can heat up better. Biut don't go too mad or you might end up with liquid all over the end of the battery - wipe it with a tissue if that happens. Sometimes it's just that the battery is getting low - I've been known to disconnect it an measure it with a voltmeter - when fully charged it's 4 volts, if it's down to 3.6 volts then it doesn't do such a good job.
Also there's the ways I use it - either
1. I suck the vapour into my mouth (usually tastes sweet on the way in, if it's working), then take in a bit of air, and mix it slightly with my tongue, then inhale.
Or,
2. I just inhale direct from the e-cig, but allowing a little air into the vapour by not closing my lips too tightly round the cig.
Also, particularly with method 1., I find it works better when the atomiser has got nice and hot - there's a 5-second timeout built into the battery, so I kind of cheat, I keep briefly stopping the flow, because my e-cig (Gamucci Micro) doesn't force a minimum stop time before letting it work for another 5 seconds. Again, it's important not to go too far - I actually had slight burns to my lips, so now I'm a little more sensible, if the metal between the cart and the battery is getting really hot, I'll stop and let it cool down. Most likely, if I've had to do that to get a proper hit, there's something else going on that's stopping it working, probably the cart has run dry, or the liquid is too far away from the atomiser to get hot enough.
In theory my methods might ruin the atomiser, making it so hot and getting so much liquid on it, but so far it's holding up well to this "abuse." I haven't even bothered to clean it. I guess a lot depends on the purity of your liquid. Also, high temperatures may mean greater health risks if the e-cig materials are getting hot - you don't want to rupture the battery and inhale that8-o - but I've had no cough since starting to do these things, and the result tastes like a fairly pure nicotine hit to me - a good clean tingly feeling in my throat, it doesn't feel unhealthy. But really, please proceed with caution if you follow my tips.
Also, it could be my body that's getting used to the hit, like any drug you might end up taking bigger and bigger doses for the same effect. Best way to keep an eye on that is to watch how many times you need to recharge the batteries, and how much liquid you're using per week. Even at the end of all that, not every toke is a good one, but it seems to be getting more reliable for me.