Most of the time, I use affiliate links. As an Amazon Associate I earn from qualifying purchases. I'm also enrolled in Rewardstyle and receive commision when you use my links. Frequently, I also use referral links for some retailers. Those links usually provide you a special offer, and I am compensated as well.
The ads on my sidebar and within posts are also pay per click, and I receive a small amount of money when you click on the ads. All the money invested usually goes right back into the blog for your enjoyment!