Put it simply:

1. Design your architecture, make it clear of what module your services are made of, how are they related to each other
2. Deploy a load balancer cluster (nginx or LVS or both), run your applications behind them
3. Choose an automation system (ansible, saltstack), automate the deployment of your application
4. If everything above is OK, subtle performance improvements could be considered

I don't want to sound rude, really... but there are literaly whole university degree courses that revolves around software engineering. There's no way a question so vague can get a proper, deep and satisfying answer.