Depends somewhat where you live and what you plan to do with the Bitcoin (long term hold or actively trade).. but major exchanges in major countries are pretty trustworthy these days.
Kraken, Gemini, and Coinbase are all quite trustworthy, if any of those are available in your locale.
Buying and holding for 4+ years has produced amazing gains in Bitcoin since its inception. Trading often and fooling around with alt coins has caused many great losses and pain. Don't invest more than you can stomach losing or holding in the red for a few years.
Kraken, Gemini, and Coinbase are all quite trustworthy, if any of those are available in your locale.
Buying and holding for 4+ years has produced amazing gains in Bitcoin since its inception. Trading often and fooling around with alt coins has caused many great losses and pain. Don't invest more than you can stomach losing or holding in the red for a few years.