Basic requirements for the visa application are the following:
1. Completed Schengen visa application form.
2. Passport or official travel document (validity exceeding the intended stay by at least three months, two blank visa pages, issued no more than ten years ago).
3. Valid proof of residency in the country of application (visa/permanent residence card/passport).
4. One recent passport picture according to the photo requirements.
5. Flight itinerary (reservation in your name, ask for confirmed airline reservation).
6. Visa, residence permit, or passport to enter the next country after visiting the Schengen area.
7. Medical insurance
8. Paystubs covering three months’ salary.
9. Employment verification, stating: position, duration of employment, monthly income, and approved period of leave (students: proof of school registration). If self-employed a business license and tax return forms are required.
10. Proof establishing the purpose of your trip.
11. Fee.
12. A prepaid self-addressed label if you want to have your passport sent back to you.
To support your case, you can provide other documents and/or written explanations as well, such as:
- school classes registration,
- school acceptance letter,
- letter of recommendation,
- letter of invitation,
- affidavit of support,
- lease agreement,
etc.
Here is a similar thread:
Germany jobseeker visa requirements.
The processing of visa applications usually takes up to 15 days.
