Since I’m from the States, I usually purchase Bitcoin through Coinbase and Gemini. I generally favor Gemini for immediate purchases once you initiated. Coinbase takes a bit longer (usually about a business week) and could place you at a disadvantage if your attempting to conduct impulse purchases. Once you are more familiar with exchanges, Kraken is another viable option. If you do not reside in America, resort to the bitcoin dot org website and which can generally guide you which reputable exchanges to acquire Bitcoin. I believe Bitstamp is a well established international exchange so you may get lucky. Also, your country may have ATM’s where you can purchase with fiat. The fees are higher but they tend to provide better anonymity.