1) Copyright Issues

Copyright is a legal concept, enacted by most governments, giving the creator of an original work exclusive rights to it, usually for a limited time. Generally, it is "the right to copy", but also gives the copyright holder the right to be credited for the work, to determine who may adapt the work to other forms, who may perform the work, who may financially benefit from it, and other related rights. It is a form of intellectual property (like the patent, the trademark, and the trade secret) applicable to any expressible form of an idea or information that is substantive and discrete.  [see: World Intellectual Property Organisation. "Understanding Copyright and Related Rights". WIPO. pp. 6–7.]
Since you are writing your dissertation in Germany, you must adhere to the German copy right law (Gesetz über Urheberrecht und verwandte Schutzrechte).

- How to cite

For every fact, information, idea and data you did not create yourself and that is not declared as common knowledge you always need to acknowledge the original source. For example, if you use data from a scientific experiment conducted and reported by a researcher, you must cite your source, probably a scientific journal, a book or a website.
Citation has several important purposes: to uphold intellectual honesty and avoiding plagiarism, to attribute prior or unoriginal work and ideas to the correct sources, to allow the reader to determine independently whether the referenced material supports the author's argument in the claimed way, and to help the reader gauge the strength and validity of the material the author has used.
A bibliographic citation is a reference to a book, article, web page, or other published item. Citations should supply every detail to identify the item uniquely.

How to cite (including citation styles) and how to avoid plagiarism are part of the curriculum at the library training. The course is available online. (In German.)

- Using images, photos, charts, illustrations, figures and tables

If you have created the original image or photo, you are the rights holder and you may use the image in your thesis.
Unless:
You have assigned it to someone else.
You have photographed, copied or scanned something in which the rights are owned by someone else (e.g. pages in a published book).
The image is a photograph of any people (You need formal permission to use the photo!)
If someone else created the original image or photo, you need to seek permission from the photographer or rights holder. By previously published images etc you always need to make sure that you have a written permission from the publisher or copyright-holder to reproduce the figure.

- Publishing  your work

Before you publish parts of your thesis or partial results, please make sure you always request a printing-permission at the dean's office (Promotionsbüro).
Writing a cumulative dissertation needs further attention at the time of the final printing:
You need to have the publisher´s permission to “reprint” your own papers. Most publishers allow their authors to deposit a copy of your article at an institutional repository. If the author does not have the right to use this material, then the file must contain a list of references and, if possible, a DOI link to the original version (e.g. the link to the following DOI 10.1016/j.ddstr.2007.08.003 would be http://dx.doi.org/10.1016/j.ddstr.2007.08.003).

2) Types of scientific misconduct

See: Wikipedia, The Free Encyclopedia "Scientific misconduct."

3) Ethical Adjustment and Manipulation of Images

In accordance with the policy and recommendations of major scientific journals in our field, it is strongly suggested to follow specific guidelines when images, including macro- and microphotographs, X-rays, Western-, Southern and Northern Blots as well as comparable images are digitally adjusted.
A helpful discussion including several examples and links to relevant journal policies is available at (Rossner and Yamada, 2004. The Journal of Cell Biology Vol. 166 no. 1, 11-15):
http://jcb.rupress.org/content/166/1/11.full

4) Authorship and Contributorship

Who should be first-, last- or co-author on a scientific publication, including journal articles, posters and web-based presentations? Helpful advice on this common issue is provided by the International Committee of Medical Journal Editors (ICMJE) at the following link:
http://www.icmje.org/ethical_1author.html

5) Recommendations for a laboratory note book

Laboratory note books (originals) have to be archived for at least ten years in the lab where the data were generated. Copies may be produced and handed to the person who generated the data at the time when she/he leaves the lab. The note books need to have continuous page numbering and firmly connected pages without the possibility to remove pages without traceability.

6) Ombudspersons

By questions or suspect scientific misconduct please feel free to contact one of the Ombudspersons of the Department of Veterinary Medicine at the Freie Universität Berlin.

More detailed information you may find here.