I wanna give some credibility to what I am going to tell you, I am a 3.9-4.1k tank main.

So, Surefour has a video on consistently that is really great. I would recommend watching it. But for what I do to stay consistent and to get ready for comp is I play 3-5 games of quick play to get warmed up and then hop on a low masters smurf to play a game or two on to see if I am feeling overwatch.

I would also recommend you go over and watch your VODs from last night to see what was different about those games and different (in a positive way) in the plays you were making.

Overall, consistency is the hardest thing imo to achieve in game and real life. Our body and mind react to different things and different stimuli when we are doing something, or it craves certain stimuli when doing an activity. If you can remember what you did before you entered competitive and during and so that every time, that may be a good way to start off with getting into that mindset.