• Always stick with regular and trusted online wallet providers such as Blockchain.com wallet, Coinbase wallet.
• Never forget your wallet password.
• Never disclose or share your wallet password with a second party.
• Be sure to have your 2-factor authentication done as added security for your online wallet.
• Keep your 12-words wallet recovery phrases safe, they would come in handy when wallet passwords are unavailable.
• Always trade on trusted exchanges like nairaex.com. 
• For added security: Get a cryptocurrency hardware wallet.