weeellll.. all I can say is that it takes proper timing and the perfect reflexes. for me when i use a jutsu that charges up the computer trys to retaliate especilly if it its sasuke. I get alot of clashes out of the blue too.
I try to get to the opposite end of the field from my opponent and then when they charge, at least I can see them coming from that far, I retaliate and voila....jutsu clash^^ Works best with people who charge like sasuke's chidori or Naruto's rasengan. Yellow Flash's rasengan doesn't work fully charged because he teleports behind the opponent ruining the chance of a clash.
It usually takes me by suprise anyway, and I don't start button mashing early enough because I don't realize I'm in a jutsu clash, making me lose.
That's why I start on the opposing side if I can help it. Also, if you wait until just before they hit you and release your technique then you immediately start off with an advantage on the jutsu clash (your bar will be bigger than your opponent's). It all depends on releases it last and who travels the farthest to a jutsu clash. If you see a clash coming but you know your jutsu will BARELY connect for a clash, don't do it if you know you can't make a full recovery with your opponent's bar practically full.