you know, i was taught that it was improper english to put 'and' or 'because' at the start of a sentence too, because they're connectives, used to bridge two phrases or sentences; but that doesn't stop me ignoring the rule because i write / type how i speak. same thing with commas before 'and's. it's not proper english to put a comma before an 'and' but sometimes a pause is needed before the 'and' so i put a comma there.