Scaling Databases and Servers

Scaling Databases and Servers

If you had a server and database that was getting way too much traffic,
for lets say a simple online game, how would you consider scaling the
server and database?
My thoughts are to future-proof it and scale both the server and database
horizontally. I know this creates much greater complexity, but I feel like
it's the best option.
Can someone offer me their thoughts? How would you identify the
bottlenecks and issues within the database? What are the main things to
look for before jumping in and scaling? How would you scale the server?
How would you scale the database?
Thanks :)