Doing things for others with てあげます/てくれます/てもらいます, and くれます (give to me).
て-form + あげます = do a favour for someone else.
わたしは ともだちに ほんを かして あげました。
I lent a book to my friend (as a favour).
て + あげます shows the action benefits someone else, done by the speaker or their side. Be careful: said directly to a superior it can sound condescending.
て-form + くれます = someone does a favour for me/my side.
ともだちが てつだって くれました。
My friend helped me (for my benefit).
て + くれます is used when someone does something for the speaker (or their in-group). The doer is marked with が; the speaker as beneficiary is usually unstated.
て-form + もらいます = receive the favour of someone doing something.
わたしは ともだちに みちを おしえて もらいました。
I had my friend tell me the way.
て + もらいます is from the receiver's viewpoint: I get someone (marked に) to do something for me. くれます marks the doer with が; もらいます marks them with に.