Key point
Start with the output
A good starter ML problem has a clear input and one target output. If you cannot write the target in one sentence, the repo will become confusing fast.
Before you think about algorithms, decide what the model must predict: a category, a number, or something you should not model yet.
Two starter shapes
Most first scikit-learn projects fit one of two shapes. Classification predicts a category, like spam or not spam, pass or fail, high risk or low risk.
Regression predicts a number, like house rent in rupees, delivery time in minutes, or marks from study hours. Both are valid. Pick the one that matches your target.