Effective Toking - This is what I do

1. Pre-toke checks - juice level, airflow ring position & mod (correct setting & battery level)

2. De-pop & pre-warm the tank, either by holding the fire button whilst not toking (see here for demo), or using a reverse toke as mentioned in the video here

3. Take a couple of deep breaths, ending with lungs exhaled

4. Put the mouthpiece to your lips ready to toke, press & hold the fire button and after a slight pause, aim to feed in the toke to with the start of simmering sound from the coil.  If you de-popped/pre-warmed the tank with either of the above suggestions, the pause might be ½ sec or less, or over a second if you haven't.

5. During the toke, listen for the unmistakable "gentle roaring sound", meaning you have a good toke rate (note, this can only be sensed properly using Dimitri juice, not straight PG/VG).  On higher Wattages/dual coils, also expect to feel significant warmth from the vapour in the lungs.  If it feels uncomfortably hot, pull the toke a bit harder to suck in more ambient air

6. Keep the toke going,  counting "one thousand and one, one thousand and two" to get an idea of toke duration.  Keep in mind the exponentially rising punch from longer tokes.  I try to aim for 6-7ish second durations (but working up gradually)

Toke rate Basically, how hard to suck on the mouthpiece. It's essential to get this correct for your Wattage, coil and tank.  Too hard drastically weakens the effect, and too slow, especially at higher wattages can result in uncomfortably hot vapour and lack of trip euphoria.  If you're moving from a single coil setup to dual, be aware you'll need to toke harder than you're accustomed, but it's still easy to toke too hard

Toke Duration  Increasing duration of the toke will have an approximately exponential effect on the trip intensity, provided the Wattage/toke rate is optimised and the vapour sufficiently held in the lungs.  See this part of the vid for details.  Be careful when taking long tokes,  Build duration gradually, they can be unexpectedly powerful.

Unusual Coil Noises Get used to how it sounds when working at optimum Wattage/toke rate. When upto temperature with a good toke rate this should be a gentle roar (I guess this is caused by vapour turbulence in the long driptip), with a gentle simmering coming from the coil, perhaps with the occasional spit or two.  If the coil starts making unusual sounds (e.g, fierce boiling or loud hissing), stop toking immediately and check over the tank/mod to find the cause.

Flooding If you're having problems with gurgling, lack of vapour despite ample wattages, juice ingestion, tank mysteriously warming up, or leaking when inverted, then it's likely that juice has entered the inner chamber (i.e. flooding).  A sharp blow down the mouthpiece should clear the worst of it, but unless you've set up the tank properly it'll probably recur.  Refer to the setup guides as linked from the site RTA section - most common mistake is insufficient cotton in the juice wells, see this part of the latest RTA video for an explanation

Monitor The Juice Level The pre-toke checks (see above) cover this. In some conditions, juice level can fall much faster than expected (e.g repeated tokes using dual coils below their efficient working range). The lowest safe level for tanks varies with the tank and how it's been wicked (see this part of the video for my take on the Dead Rabbit V3 RTA), but watch for inconsistent potencies, unusual or lack  of coil noise, odd tasting vapour & unusual trip effects. Dry hits can ime have extremely unpleasant consequences, so I suggest awareness to nip them in the bud.  

When The Tank Runs Low I suggest topping up a little with straight PG/VG and making the best of the weaker juice.  Potency loss can be offset to some degree with any spare Wattage headroom (upto wirebuddy's max) or increased toke duration.

Changing Wicks/Coils Before refilling with fresh Dimitri Juice, I suggest cleaning/washing the entire tank in isopropyl. As well as replacing the wick, I also tend to replace the coil, but if you're careful when extracting the old wick then it'll generally be fine to re-use the coil once confirmed OK with the usual red heat burn, heating evenly/gradually from centre outwards