Ask HN: What is your advice for a DevOps newbie?

I'm joining a bootstrapped startup (online service) that just applied for (and received) Series A funding. As we're growing pretty fast (around 10 million users currently), we need to bring down the infrastructure costs and ensure continuous delivery & uptime. I'm graduating in may and currently playing with various tools including Puppet, Chef, Ansible and Salt. I'm more in favor of Ansible right now. So, what tips/advise would you have for me? 😃