By my third flight I was expected to remember and proceed through the pre-flight checklists (acronyms ABCD and CBSIFTCBE). So I swallowed hard and had a go. And I managed to remember them all, if a bit haltingly. Another little milestone. This reminds me of the acronyms you use at school like the fictitious chap ROY G. BIV (the colours of the spectrum), or the computing acronym PCMCIA which can be translated as 'People Can't Memorise Computer Industry Acronyms'.
When the canopy has been closed, one of the ground helpers comes up to the nose and waits. When you are through all the checks and ready, you yell 'airbrakes closed and locked, ready for tow'. You pull the cable release knob and shout 'Open', they place the tow rope ring into the receptacle under the nose and shout 'Close' and then give the rope a good tug to check it is indeed secured. On the first flight of the day you should insist on a positive release check like this. The shouting is mainly because you can hardly hear through the closed canopy (hand signals can be used if necessary - and if club members have adipted an agreed set of signals). At that point the wing-man checks that it is all clear above and behind and signals to the tug to take up the slack then to go all out, trotting along keeping the wing-tip off the ground until you are going fast enough (i.e. when he has to start running) - and you are away...
Early in training it is easy to forget something. Here are some examples:
After nine flights it was routine for me to go through the ABCD and CBSIFTCBE pre-flight checks, and ask for the tow rope to be connected, which is the normal sign that you are ready to go. The wing-man lifted the port (upwind) wing ready for us to roll. He signalled the tug to take-up the slack and it slowly moved ahead of us tightening the tow-rope, then stopped again. And then we just sat there.
And sat some more. I looked around to see if there was a reason for the
delay. Nothing obvious. About a minute later I realised something must be
wrong. I glanced around the cockpit again and - oops - my harness
was undone ! I had laid it into position but not buckled up the leg or
shoulder straps. I quickly pointed this out to the instructor - who I now
realised had known this all along (sitting behind me I assume it was easy
to see the undone straps). He lifted the canopy to formally indicate we
were not ready after all, and we exchanged a few 'pleasantries' with the
wing-man at my expense. For my sins I had to start all the checks again
from the start. As we went through them, I realised all the checks except
security (straps) had a tactile element, e.g. testing the control
movements or touching the instruments. With my parachute strapped on a
little tighter than usual, I had no sensation of not being tied down. So
from now on I vowed to give the straps a tug at the appropriate checkpoint
! 
Before boarding the glider I walked around for the usual ABCD checks (Airframe, Ballast, Controls, Dolly), installed the usual pair of hard cushions at the seat back, slid the rudder pedals fully rearwards and screwed a ballast weight onto the front cabin floor (the price to pay for being vertically challenged). Then I climbed in and waited for the instructor to follow me into the rear seat. But he was still lying in the sunshine on the grass a few yards away. I reckoned he'd had a hard morning and I sat waiting quietly for him to steel himself for a flight with me.
After a couple of minutes I started to get suspicious. The instructor had a beady eye on me, and he said "Is this glider safe to fly?". I rambled on about how I'd done the ABCD checks and I'd seen it go through the Daily Inspection (DI) earlier, so I believed it was safe. "Are you sure it's safe to fly?" he asked again. I was running short of ideas. He noticed my furrowed brows and leapt to his feet saying "Have you checked the log book?!". I had not. Indeed, until now I'd never checked it. He told me that from now on I should check it every time I flew, as one day that might save my life. The previous flyer could have written in something like "Landed very hard, check airframe before flying again!", or "Altimeter inoperative". The glider might not be flyable or it might need special allowances. I had a look at the book and the DI entry was there as expected, and thankfully nothing had been added so we were safe to fly. He added as an afterthought that if you get into a glider and the log book is on the seat, this usually indicates there is a serious problem.
The instructor said he would fly the take-off. I ran through the pre-flight checks. When I reached the 'Eventualities' check I started rambling about what I'd do if we had a rope break at various heights during the tow - until the instructor pointed out that since he was flying, he would handle the eventualities. And if in future I was performing the take-off then the normal eventuality in the event of trouble is simply to hand back control smartish to the instructor ! But he admitted there was no harm in discussing what the eventualities are, so long as you make clear who will execute them if necessary !