Here is some solid advice in this article 

https://bitcoinmagazine.com/sponsored/the-dos-and-donts-of-bitcoin-self-custody

Casa wallet is pretty good for beginners, you can even upgrade to their multisig solution in the future once you are comfortable with self custody 

https://casa.io/learn-more/self-custody

Unchained also has good content on this

https://unchained.com/features/singlesig-vs-multisig