Be confident, make sensible decisions based on the best facts available then stick with them unless it becomes blatantly obvious you're wrong. Shouldn't happen too often but when it does, figure out why you got it wrong and then go through the process again. Learn from experience. When you do cock up, don't dwell on it, take the lessons but concentrate on what's coming, not what's just happened. Communicate and keep your crew and ATC on your side. Be humble.
It sounds at the moment like you're trying to second guess your trainers to fly like they want rather than having your own ideas. That approach will never work in the long run. Fly the aircraft as you want to fly it and take what you can from the advice of the trainers and line captains you fly with. Always think as though you were the captain, ie "what would I do in this situation." and learn from what the captain actually does, bad solutions and good solutions are equally useful to you.
Be yourself, don't put on an act and good luck.