One of my favorite heroes in the game. It's all about being quick and efficient. By 6 you should have 3-1-1-1, take that point in Phase Shift at 1 or 2. You can dodge so many things for ZERO MANA! It is easily Puck's best skill. Here is a list of only SOME of the things you can dodge:
Ranged right clicks
Shadow strike
Scream of Pain
Sonic Wave
Storm Bolt
Spirit Lance
Chain Frost
Finger of Death (dodge window is extremely small, but possible)
Laguna Blade (similar to FoD)
Earth Spike
Impale
Last Word (watch the debuff timer, hit it right before it ends to avoid damage as well as silence and disarm)
And much much more!
Remember silence breaks channeling spells, so if you see Sand King charging up an ult or in his Sandstorm, blink on him and silence him. Dream Coil breaks channeling on initial cast and the break stun. You can stop TPs with it, like S4 did in the grand final of TI3.
Blink is the best item you can get, especially once you have 3-4 points of Phase Shift. You can use it to wait out the 3 second damage cooldown on Blink then Blink immediately, or shift queue it.