take care;
be careful;
be cautious;
be careful in;
be careful of
例如：小心点，别湿了衣裳。
Be careful! Don't get your clothes wet.
Don't worry yourself about me, I can take care of myself
你别担心我，我能照顾好自己。
小心轻放！
Handle with care!
小心，危险！
DANGER!
小心，别滑倒了。
Be careful not to slip.