The first few days of ownership of any phone will render battery life short.
So far I've been able to get just short of 3 days of battery between charges. It all comes down to "dumbing down" your phone when you don't need the smart phone features. Now before I say anything, if you NEED/WANT to know you've gotten emails the second they arrive, need/want instant Facebook and social networking updates, or anything along those lines, when I'm saying will not help you what so ever.
I would start by going into the developer panel and turning off the flashy features - transitioning, animations, etc, turn off the stupid screen saver (I never got the point of those aside from further showing off your phone), lower the duration of your screen time out, and lowering your brightness are just a fey key things.
Next to that, get into the Google Play store and disable auto updates. If you want apps to auto-update, change it to only do so via Wifi. Along side that, disable wifi when you're out and about. I'd even go and disable Mobile Data unless you're using it. You can Use Widgetsoid to put a simple toggle on your home screen to turn on/off Mobile Data a bit easier.
Turn off other features you're simply not using - Bluetooth, GPS, etc. Disable Google Now / SVoice unless you use them often.
Lower the latency of your apps checking for notifications.
Disable your Vibration, unless you actually use it. Vibration is a nice way of quickly lowering your battery.
And of course disable/uninstall apps you simply don't use or want. Aka remove bloatware.
Those are the basics.
To get down to the nitty gritty, I suggest you find location profile apps that "control" your phone under certain situations. For example, I like Lama. You basically establish "if then" statements and the app controls the phone accordingly. For example "When Car Bluetooth connected, disable wifi, disable vibrate, disable sync, increase ringer volume, brightness at 30%" OR my favorite "When Work Wifi is detected, disable Mobile Data, Toggle Sync every hour, lower brightness, disable ringer and vibrate, enable Power Saving Mode". You can even add times; "At 10pm show notification - if ignored, open app [Ultra Power Saving Mode]"
I have many other profile, but you get the point. You enter the parameters and it controls the phones when those parameters happen. The more time you spend "perfecting" it, the more it does and often the more battery you have to play with.
That's roughly it off the top of my head. Of course you do what works for you. I'm not a power using (often), so I don't need to take advantage of all the S5 has to offer every minute of the day.