Loops
In python you should rarely use while loops or for x in xrange(n) loops. Python has a wide variety of tools like zip, enumerate, itertools.* to iterate over pretty much anything with a for loop and an iterator.
Don't write
for x in xrange(len(data)):
print data[x]
instead write:
for item in data:
print item
Don't write
for x in xrange(len(data)):
print x + 1, data[x]
Write
for index, item in enumerate(data):
print index + 1, item
Don't write
for index in xrange(len(data)):
print data[x] + data2[x]
Write
for item, item2 in zip(data, data2):
print item + item2