One of the most common reasons for rejection is applying to the wrong embassy. The rule is straightforward but often misunderstood: you must apply for your Schengen Visa at the Consulate of the country that you intend to visit. If your travel spans multiple countries, you must apply at the Consulate of the country where you will spend the most days (the primary destination).
If you plan to spend an equal amount of time in two different Schengen countries, you must apply at the Consulate of the country whose external borders you will cross first upon entering the Schengen Area.
Embassies need assurance that you can support yourself during your stay without resorting to public funds or illegal employment. The specific daily amount required varies by country (e.g., France requires around €120/day without prepaid accommodation, while Spain requires €108/day).
You must provide bank statements from the last 3-6 months. Large, sudden deposits right before applying raise immediate red flags unless accompanied by a clear, documented explanation (e.g., sale of a vehicle, inheritance).