That may be true, but . . .

I may be wrong, but . . .

You might be right, but . . .

You have a good point, but . . .

You could say that, but . . .

Correct me if I'm wrong, but . . .

I don't mean to be rude, but . . .

I hate to bring this up, but . . .

I don't mean to be negative, but . . .

This may sound strange, but . . .