Often, you don't need to customize a program, just take advantage of the features that already exist. Be honest with yourself. If you make guesses that seem to work, then you're pushing your luck. Better to call in the cavalry now than to wait until your project fails at a critical time. Limit the complexity of your work.
Complicated projects are an invitation for disaster for amateurs.
Even if this isn't an important project, you can waste a lot of time on a complex program and end up only with heartburn. Remember that you have a job beyond computers. Some people get sucked into the puzzles of programming, and forget they have other responsibilities. Don't let your personal interest outweigh your common sense. Don't attempt mission-critical projects.