Using android is not a bad idea as a crypto wallet. To be honest i'v seen lots of people who use android wallet to keep their bitcoins but when your portfolio start getting bigger, there is a need to move you coins to a airdropped device which is considered more secured than an android wallet. Making use of a hardware wallet is recommended and that is when you feel you may have to increase your portfolio to a more valuable holdings,  then you can buy a hardware wallet and safeguard your coin. One of the best ways of storing your bitcoin seed phrase is manually with a paper or any writing material. Your seed phrase should be far away from the internet, so making use of cloud storage systems is not recommended.