1. Explain it simply
互相 (hùxiāng) means 'mutually' or 'each other'. It marks the action as reciprocal - it goes both ways.
The subject must be plural (我们, 他们, 同学之间...), because at least two sides take part.
Word order: plural Subject + 互相 + verb, as in 我们互相关心 (we care for one another).
Keep 互相 in front of the verb; it cannot go to the end of the sentence or split the verb.
2. Show examples
同学之间应该互相帮助。
Tóngxué zhī jiān yīnggāi hùxiāng bāngzhù.
Classmates should help each other.
plural subject 同学之间
我们互相关心。
Wǒmen hùxiāng guānxīn.
We care for one another.
互相 sits before the verb 关心
两个孩子互相照顾。
Liǎng gè háizi hùxiāng zhàogù.
The two children look after each other.
the caring goes both ways
3. Share a tip
互相 needs a plural subject and sits before the verb - say 互相帮助, not 帮助互相, and never use it with a single person.