Before you start analyzing real-world data, make sure you have a basic idea what your data look like. How many cases and variables do you have? Do their frequency distributions look plausible? Do you have any string variables and do you need to set any missing values?
A quick data inspection takes little time and effort and may save you a lot. Analyzing your data becomes faster and more satisfying when you know you're in control. The tutorials below will get you there fast.