A clean scan is smaller, easier to read and less likely to be rejected than a quick photo of a crumpled page.
A casual photo of a document is usually tilted, shadowed and full of the table it is lying on. That wastes file size on the background and makes the text harder to read. A proper scan crops to the page edges and evens out the lighting, which is why it is both clearer and smaller.
Most phones can do this already. The Files app on Android, the Notes app on iPhone, and several free scanner apps will detect the page edges, straighten the page and save a PDF.
Lay the document flat on a plain, dark table so the page edges are easy to see. Smooth out creases. Make sure there is bright, even light across the whole page; daylight near a window works well. Avoid your own shadow falling across the paper by holding the phone directly above the page rather than at an angle.
Keep the page square to the camera. If it looks like a trapezoid on screen, the text on the far side will be smaller and blurrier.
For printed text, such as a marksheet, an application form or an ID letter, black-and-white or grayscale mode produces much smaller files than colour, often a fraction of the size, with text that is just as readable.
Use colour only when colour matters, such as a stamp or seal that has to be visible, or a photograph on the page. If a form insists on colour, keep the scan to one page per file if the limit is small.
Check the form. Some ask for a single combined PDF, others for one document per upload. If you have to combine pages, scan them in order and check that none is upside down before you save.
A multi-page scan grows quickly. If you are close to a limit, remove blank or duplicate pages first; that often saves more than lowering quality.
Open the saved PDF and zoom to about 200 percent on the smallest text. If you can still read it comfortably, the scan is good. If it is blurry, rescan in better light instead of shrinking it further.
Then compress the file to the size the form allows. The compressor linked below steps the quality down only as far as it needs to, and does the work in your browser, so personal documents are never uploaded.
For printed text, yes. Black-and-white or grayscale scans are much smaller than colour and just as readable. Use colour only when a stamp, seal or photograph needs it.
It depends on content. Text-only pages are small, while scans of colour pages are large. A cleaner, grayscale scan always fits more pages than a rough colour photo.
Most often because the pages were captured at a very high resolution or in colour. Re-scanning in grayscale or compressing the PDF reduces it a lot.
Only if the tool does not upload them. Tooqly compresses PDFs in your browser, so your documents never leave your device.