Duration

Use por when you want to talk about a length of time (the duration of something).

🎶Te amaría por mil años más.🎶

I'd love you for a thousand years more.

"Amarte por mil años más" de Yadi Fernández

Reason (because of)

Use por when you want to express a reason for doing something.

🎶Y es por tí, que late mi corazón.🎶
And it's because of you, that my heart beats.

"Es por tí" de Juanes

Exchange
Use por when you want to talk about an exchange or a substitution.

🎶Quisiera cambiar mi corazón por otro que no te esté amando.🎶
I would like to exchange my heart for another one that isn’t loving you.

"Cambio mi corazón" de Grupo 5

Action
Use por when you want to talk about where an action takes place.

🎶Ayer la vi, bailando por ahí con sus amigas en una calle de Madrid.🎶
Yesterday I saw her, dancing around with her friends on a street in Madrid.

"Bailando por ahí" de Juan Magán

Means
Use por when you want to talk about means of transportation or communication.

🎶Si me llaman por teléfono, no estoy.🎶
If someone calls me on the phone, I am not here.

"Si me llaman por teléfono, no estoy" de Gustavo Santaolalla

por favor

please

por eso

therefore / because of this

por supuesto

of course

por ejemplo

for example

por lo general

in general

por la mañana (por la tarde, por la noche)

in the morning (in the afternoon, in the evening)

gracias por . . .

thank you for . . .

Purpose (in order to)
Use para when you want to express purpose.

🎶Yo solo quiero pegar en la radio, para ganar mi primer millón.🎶
I just want to be a hit on the radio, in order to earn my first million.

"Mi primer millón" de Bacilos

Effect
Use para when you want to express a goal or the effect something has on something else.

🎶Yo romperé tus fotos, yo quemaré tus cartas, para no verte más.🎶
I will rip all your photos, I will burn all your letters to never see you again.

"Para no verte más" de La Mosca Ts Ts

Recipient
Use para when you want to talk about the recipient of something or an action.

🎶Mil rosas para mí.🎶
A thousand roses for me.

"Rosas" de La oreja de Van Gogh

Future dates
Use para when you want to talk about deadlines, or moments in time in the future.

🎶¿Qué dejaremos para mañana?🎶
What will we leave for tomorrow?

"Para mañana" de Amanda Miguel"

Employment
Use para when you want to talk about the organization or person you work for.

🎶Ella trabaja para mí🎶
She works for me.

"Ella trabaja para mí" de Polanski y el Ardor

Conclusion
Use para when you want to express a conclusion you have made about something or someone or to share your opinions.

🎶Para mí, tú eres un cobarde.🎶
For me, you are a coward.

"Cobarde" de Yahaira Plasencia

Toward (a specific destination)
Use para when you want to talk about going to a specific place.

🎶Vamos para la playa, para curarte el alma.🎶
Let’s go towards the beach in order to heal your soul.

"Calma (Remix)" de Pedro Capó & Farruko

Bonus! The second para in this line is used to express purpose.