Search for and hire the best expert witnesses available and then keep the tightest rein possible on each of them. None of your experts should even think about doing something, writing something, or saying something, and certainly not spending any money, without checking with you first to pre-approve it. Avoid familiarity with opposing counsel. Friendly is not a term your client should think of when describing your relationship with your opposing counsel. In court, argue to the judge about your opponent's arguments, not about your opponent.
Judges abhor bickering between counsel.
Imagine a coin balanced on its edge in the center of a circle, heads facing north and tails facing south. As the trial lawyer you are stationed at one of the poles and your opponent is at the other. During the trial, the jury is walking around the circle hearing, alternatively, you and then your opponent, describe opposite sides of that same coin. Each of you is arguing accurately what you want the jury to see inside that circle. At the conclusion of the trial the jury will tell you which of you were more persuasive, not what's inside the circle.