To have access to Viper as a playable agent, you will need to unlock her. She is not one of the five initial characters unlocked by default upon installation. To unlock our toxic scientist, you will have to reach beta level 5. By hitting level 5, you will unlock Viper, along with Raze, Cypher, and Breach. Due to her being a locked character for the beginning of your Valorant journey, I would not deem her the best option for beginners. However, by the time you reach beta level 5, you will have played a good amount of matches and experienced enough of the maps that Viper would be a solid choice. She has a learning curve since her abilities go beyond a "point and shoot" hit scan-styled character, but she has the ability to dominate any match she is in with some practice and training.