Scaling up/down on Nikkei futures – how do you handle it?

Been trading $N225 futures on a smaller account for a bit now, mostly sticking to a fixed contract size. I'm profitable, but the swings can be pretty wild, especially during certain sessions. I'm starting to think about scaling my position size up or down based on market conditions – maybe higher size on clearer setups, lower on choppier days.

My concern is overcomplicating things or letting emotion creep in too much. For those of you who scale, do you have a specific system or ruleset you follow? Or is it more discretionary based on your read of the day? Just trying to avoid going from a simple, profitable system to a complex, losing one.