In a former life Roland and I ran a web hosting company. We had to deal with routers, switches, KVMs, and tons of physical hardware. All of these components were expensive and depreciated quickly over time. We made big mistakes with inventory, had hardware on hand to triple our size, and generally wasted money converting too much capital into physical hardware. In short, we overbuilt and in the end were stuck with hardware that was worth basically nothing.
One car load of many physical servers from our former web hosting company, most were wiped and than donated. A few are still sitting in my basement.
You can’t make the same mistake with virtual servers.
Sure, you can still over build, but you can’t get stuck with a bunch of depreciating assets that you can’t even sell on ebay. A good rule of thumb is: if you think you need another server, spin it up. If you need a development machine, get another instance. Just remember to set aside some time each month to evaluate whether you still need all the machines your paying for. If you have a good provider like Rackspace, you can even resize computers on demand. Excess capacity for a month is not a big deal, excess capacity for 6 months is a mistake.
Don’t be afraid to duplicate your infrastructure.
At Olark we recently finished a rollout of a new backend infrastructure (backend 2). While we were building backend 2 we ran a duplicate copy of our entire backend for about 2 months before phasing out the old system. When the transition was complete we deleted our old backend, and let me tell you – creating servers with a single click is cool, but when you can decommission what would have been a rack of servers by pressing enter you see the true power of the cloud.
So my advice: spend less time thinking about whether you should spin up another instance, and more time DELETING servers 
Servers in the cloud are just one way that we spend less time on system administration, so that we can spend more time providing value to our customers. What are your tricks for getting more from the cloud?
