Scanning using an Iphone/Ipad
To scan documents on your iPhone, go to the Home screen and open Notes. Tap the + icon at the bottom of the page, and select Scan Documents from the list of the options. This should launch your phone's camera. When the camera detects the document you want to scan, it will highlight it in yellow on the screen. You can then upload directly to your Google Drive.
Scanning using an Android
Open the Google Drive app. In the bottom right, tap Add. Tap Scan. Take a photo of the document you'd like to scan. Adjust scan area: Tap Crop. Take a photo again: Tap Re-scan current page. Scan another page: Tap Add. To save the finished document, tap Done.
Organize your Google Drive
Create a folder for each class in your Google drive to help organize your files. Make sure to save work in the appropriate folder (you can even make folders for each chapter within your class folder). Use colors to highlight specific folders. Right click on the folder. Choose Change Color. Don't leave files unnamed. If there are files you will use a lot (like your notebook for math class), click the star next to the name of the file when it is opened. Starred files are easier to get to because they are organized with preference over other files that aren't used as often.