Similar to what irmamar pointed out:
| Method | Example | Use | Formality |
|---|
| voy a + infinitive | Voy a caminar. | more immediate future | more informal |
| future tense | Caminaré. | more distant future | more formal |
You should also make note of the fact that when we use the future tense in English for the near future, that is often best expressed with the simple present tense in Spanish.
I'll pick you up at 3pm.
Voy por tí a las 3 de la tarde.
It is important for native Spanish speakers to remember this as well, when speaking English.