a) Article marketing
c) Buying solo ads
Out of these three methods, solo ads is the most effective and fastest method to get the new subscriber. I buy the solo ads at the price of $0.44 per click and having a opt in rate of approx 48%.
Although has to spend some money, but i think as long as i can find a good solo ads seller with the reasonable charges, i will try use this more to generate traffic to my side.