[scaryclam]

Number one would be: tying your deployment to the cloud providers way of doing things. ECS, CodeDeploy, heroku.... it's easy to get stuck when your ops requirements grow beyond how they do things, and really hard to set up something more agnostic alongside it (especially when you have a tight budget on cloud resources).

Number two: using tech that you really don't need. Keep it simple, even if it means not using something that the rest of the industry is in love with. Figure out what your requirements are, pick the simplest way of setting it up (keeping #1 in account, because using tooling that isn't able to grow with you is worse IMO), and keep it agnostic. Then when you start to hit the edges of the capabilities, either scale up your ops understanding and start using more sophisticated things, or hire someone in to help out.

Also, I really do agree with @KaiserPro when they say to separate your infra from your deploy. It makes moving to something else much, MUCH easier when you inevitably need to.