Depends on how much security you want. If you start playing around with small amounts a mobile wallet will be fine. As soon as you invest bigger amounts you should look into getting a offline/hardware wallet.
Best wallets for securing small amounts of BTC
electrum For Desktop and Android
Phoenix LN wallets for Android
Breez LN wallet for Android and IOS
Securing Larger amounts of Bitcoin
trezor one wallet
Cold Card Hardware wallet