A few friends of mine and I went out for lunch and hung out.(=a small number) Few friends of mine know where the accident happened.(=Not many but more than one)
A few differs slightly from few used alone, which means "not many." For example, The party was attended by a few indicates that a small number of guests came to the party, whereas The party began at eight, and few attended means that hardly any guests(negligible in number) came.
A few friends of mine and I went out for lunch and hung out. Few friends of mine know where the accident happened.
As far as I know, both mean small number, not many but there is a diffrence: 'a few' means the number is quite enough to the speaker (satifies the speaker) while 'few' means the number is less than the speaker's expectancy.