Economics isn't easy. If you have gone through the past papers, you may realize that some of them are quite tricky, especially the paper of Economics1 in 2008. However, one can surmount any challenge by hard work and perseverence. As regards the books that might help you prepare, I'd suggest the following: Microeconomic Theory by Gould and Ferguson; Macroeconomics by Dornbush and Fisher; and development economics by Todaro. Also try to read Financial Times and The Economist at least a couple of time a month; both offer good analysis of economic and political events.