From stick to strip: Good practices

Try to minimize the distance between the Arduino and first pixel, so the signal is clear. A meter or two is usually no problem. Much longer and things can become unreliable.
Avoid connecting NeoPixels to a live circuit. If you simply must, always connect ground first, then +5V, then data. Disconnect in the reverse order.
If powering the pixels with a separate supply, apply power to the pixels before applying power to the microcontroller.
Observe the same precautions as you would for any static-sensitive part; ground yourself before handling, etc.
NeoPixels don’t care what end they receive power from. Though data moves in only one direction, electricity can go either way. You can connect power at the head, the tail, in the middle, or ideally distribute it to several points. For best color consistency, aim for 1 meter or less distance from any pixel to a power connection. With larger NeoPixel setups, think of power distribution as branches of a tree rather than one continuous line.