when you disagree with someone, you need to shift mindset from a statement based (I do not like this idea, x would be better than Y) to question based.

for example:

1. What are some of the downfalls of this strategy?
2. Can you walk me through the design decision you made?
3. What is the problem we are solving here?

this does 2 things:

1. Helps hone your own thinking on topics. a lot of times you may be wrong, and if you actually think through questions you have, your thinking will improve
2. forces the person to think through your questions and realize potential reasons a different approach/solution may better.

approach things from curiosity, not disagreement. otherwise, you'll be wrong much more often.