Whe i first started out online i found the hardest part was education. now having been making money online fulltime for 2 years, i find the hardest part is finding new spots to advertise.
the key is tracking,work on the places you know has high traffic that converts and bin what doesnt. also,as the internet is always changing with social media becoming more popular,its important to keep learning. even the big name in the industry still invest in themselves. keep learning and take action on that learning.