I usually increase my 1st serve if there is evidence during the set that a great 1st serve will get me a free point, ['m talking a serve that is 50-60% chance of going in. I'll miss more, but I have a 2nd serve that I just don't double fault with, I can go a few matches without 1 double fault, but no, it's not a weapon, just a good point starter. On return of serve, I make my opponent win the points, I don't go for a winner on return, just something to make my opponent move and "win" it.
I'm more likely to get free points from 1st serve and serve and volley, so I do that. I hope my opponent has nerves if I get ahead and so I make him try to hit a winner or out rally me while hitting solid shots. If I am up even by 2, I'm counting on the opponent getting inside his head and making a mistake. I try the same strat if I am behind, I will lose the tie break to winners from my opponent and patiently wait for a winner opportunity, not go for broke on the first or second shot. No, I don't win every tie break, but that's how I approach it.
Something kind of on topic, like was said before, don't change what was working. I played a doubles match last week and my partner was serving 40-0, we got there with really well placed serves and then he goes for a 100 mile serve totally out of his character and misses, almost double faults. I was just thinking to myself, why are you doing that at 40-0?! He almost double faulted, I've seen too many 40-0 doubles games go to deuce from 40-15 when the receiving team gets some confidence. Anyway, point is be flexible....It goes to what I wrote before about my serve in tie breaks, if I played a match where a different first serve was giving me 40-0 results, I wouldn't do that strategy above.