Trying to get my play just right

When i play sometimes i feel like every fold and every bet and every raise i do works out and sometimes i feel like there is absolutely no way i can win when my all ins all get called and all of them lose! I try not to go All-in all the time but in this modern game we play its tough to win hands without being aggressive at some point in the hand. I feel like i have quite a dynamic style of play and am still looking to hone my skillz but i find my opponents dont change there play much. Im just wondering how much to people think they can improve their game or do people feel they play their cards in a solid way and the rest is down to luck? i still feel like game selection is one of the most underated skills in poker and is what is letting me down on my poker journey.  Freerolls are a good game to select but cash games are where ive found the biggest noobs in poker where you can just call down with the nuts and take peoples $ . MTTs are my thing but without good game selection its hard to turn a decent profit and low stakes is such a grind. i think less is more for me . Playing less , studying more and thinking about how im going to attack my sessions for best $ profit rather than just playing the games available - planning games ahead of time and not registering / reentering anything on a whim. Good luck at the tables Mates