Depends if you have the white pieces or the black pieces;
white: 1. Nf3 - Versatile, deceptive, unassuming. Typically, blacks first move dictates the style and nature of the game. However, with 1. Nf3, white has countless systems at his disposal depending on how black responds.
- b3 (Nimzovich-Larsen attack)
- g3 (King's Indian attack)
- c4 (English opening)
against e4: 1... Nf6 - Alekhine's defense. From move number one, black is directly attacking white's center. Many novice players will over-extend themselves and start pushing their pieces hastily. Alekhine's defense is a tricky, formidable response to 1. e4, as Bobby Fischer showed us in 1972 against Boris Spassky.
against d4: 1...f5 - Dutch defense. The Dutch defense, whose famous practitioners include Aleksander Alekhine, Mikhail Botvinnik, and Hikaru Nakamura, is a dangerous response to 1. d4. Black is taking dead aim at white's kingside and, specifically, the e4 square.