Three great books of statistical advice
After taking courses in statistics, and reading textbooks of statistics, you may still find statistics confusing. What you need is not more information, but rather advice, perspective, and a guide to steer you away from data analysis traps. These three books provide what you need. All three are written for people who already have learned the basics of statistics, but are still struggling with practical issues of data analysis. All three are extremely well written in plain English (without much math), and are quite accessible to scientists. I strongly recommend all three books. Choosing between them is hard, as all three are great. The best way to choose is to read excerpts online.
Statistical Misconceptions: This book is organized as a list of common misconceptions, each one carefully explained. Read the Table of Contents, and chapters on correlation, and disproving the null hypothesis. Buy it from Amazon.
Common Errors in Statistics: It is a very readable collection of statistical advice. The Table of Contents and first chapter are free to all, and the entire book is available to subscribers of Wiley InterScience. Buy it from Amazon.
Statistical Rules of Thumb: The title is a bit misleading, as it contains only a few rules-of-thumb (approximate formulae for doing quick, but approximate, analyses). Most of the book is more general advice and warnings. Read the table of contents and the chapter on sample size calculations. Buy it from Amazon.