If even Novak can struggle to deliver on 2nd serves at crucial times does that mean that we are all doomed to failure on some" big points"? "Yes" would be my answer , but how can we minimise the double faults or just poor 2nd serves at crucial times?
A 2nd serve is a bit like a 3 foot putt in golf in that the shot is largely determined by 2 things.Your thought process whilst setting up to play and where your focus is throughout the execution. So what do I mean by that?
Developing an effective and helpful thought process.
A poor thought process before initiating the 2nd serve might include stuff like "Just get it in" or "Don't miss here" or "How bad will I look if I miss this" etc etc. Sound familiar? We need to replace these thoughts with various forms of body awareness and feelings to allow us to perform. For example you could loosen your grip on the racquet or breathe in and out deeply. Make sure you bounce the ball the same number of times or pull at your underwear! (Now who would do such a thing?) It doesn't really matter what your routine is as long as it doesn't involve you putting pressure on yourself by trying to be good and not fail! Listen to yourself and try to become aware of what you are saying to your inner self and most importantly, if this is helping! Self awareness is the first step to having any hope of improvement. The thing about mentally tough players like Novak is that they find a way to get back on track even after choking on big points. Their self awareness is quite phenomenal and ability to refocus on helpful thoughts is amazing. Yes the routine might look a bit nutty but it's only done to help them get into the right frame of mind.
What to focus on during the action of the 2nd serve?
So you've managed to develop a solid routine which allows you to do all that may be required to then execute the 2nd serve but then you actually have to go and do it!! So, what should you focus on throughout the execution? As little as possible since all the hard work has been done in the preparation! If anything at all I would say that you stay focused on the feel and rhythm of the 2nd serve and never on "how" to do it! This could be different for everyone but when I serve under pressure (eg final set at 5-5 30-40 and 2nd serve), I try like crazy to keep a relaxed arm and accelerate up and through the hit. I try never to think about hitting it in the court as this diverts me from executing the serve with the necessary feel to allow it to happen.
(Goran Ivanisevic was asked by a bunch of keen British coaches after just winning Wimbledon about the secret of his serve and he replied as follows : " You bounce the ball a couple of times and then you put it up in the air and ... you hit it!" This was very true for Goran in general but I remember him serving at match point in the final and he struggled to relax his arm enough to deliver the final blow. He was hitting his arm and trying to relax it to be able to just "hit it" which he did eventually and won of course. So he had the self awareness to focus on the relaxation of his shoulder)
Serving is not easy at any level of the game so make sure that you find a coach who helps you develop a solid pre serve routine. Then explore your inner thoughts and feelings during the heat of the battle and see if you can come up with some alternative ones to help you just "hit it" as Goran would say ! Yes , great technique may help make it easier but not many players in the history of the game have managed to achieve the perfect serve - apart from Sampras. Most players have to serve with what they've got and when they serve better it's usually down to solid routines,rhythm and feel plus the ability to have understood what to actually focus on.