Thank you José for you explanations!! The second one is what I meant ;) muchas gracias!

En este contexto, hay una diferencia entre "No sé qué hacer mañana" y "No sé qué haré mañana" Oh man! I left my make up set at the office. I don't know what to do! (no sé qué hacer) (implying there's something you can do now, like calling the office or something) Oh man! I left my make up set at the office. I don't know what to do tomorrow! (no sé qué hacer mañana) (meaning you have no plans for tomorrow, which doesn't make sense in this context) Oh man! I left my make up set at the office. I don't know what I'll do tomorrow! (no sé qué haré mañana) (implying that there's no fix now and that you'll have to walk around the office with no make up) 自然美いいです．