What phone did you get.If it is a fast one I recomand:
Shadowgun:Deadzone ( Very good fps shooter which is free )
Swiftkey ( A much better keyboard than the stock android one, download if the phone is fast only though )
Any messaging apps which you use Facebook, outlook, facebook massanger and Skype.
Clean Master ( Needed to keep that cache low )
If you really want the Flappy Bird game or some paid apps free search for the apk of that app.
Remove all those widgets they are useless and slow down your phone.
Root it if you are into overclocking or checking out the frame rate in games.
Hope you enjoy your new android phone.