Formal:
* Espero vê-lo(a) em breve. (I hope to see you soon.)
* Estou ansioso(a) para vê-lo(a). (I'm looking forward to seeing you.)
Informal:
* Te espero! (I'm waiting for you!)
* Vou te esperar! (I'll wait for you!)
* Mal posso esperar pra te ver! (I can't wait to see you!)
* Até breve! (See you soon!)
You can choose the best option based on your relationship with the person you're talking to and the situation.