Ciro Santilli Give students answers to all questions.
Explain in extreme detail how each result was reached.
Students have the amazing capacity of not looking at answers if they don't want to.
And when they've had enough, then can read answers and understand while the problem is fresh in their minds.
If you don't give answers, no one will be able to use your online material without you being there to hold their hands.
Keep the example/theory ratio high, very, very high.
For natural sciences, add as many reproducible experiment images/videos/descriptions as you can.