• The topic I chose did not match the student's background. He was interested in forensics while I was working with wireless signals. As there is no good forensics group at our university he accepted the topic. Nowadays I would adjust the topic or not supervise the student. And, wow, forensics, I could definitely need that knowledge!
• I underestimated the topic's complexity. Students often underestimate this but as a supervisor you are responsible for planning a topic that is feasible to finish within time. If you are not sure how much work something is, the thesis goals should be flexible. "When the thing I imagined finally works!" is not a good definition of such a goal. The worst part was that it got too close to low-level signal processing, which neither me nor the student expected that topic to be, and then a colleague of mine joined for thesis co-supervision.
• I underestimated how hard writing a thesis is. Especially for someone who is not good at writing. My colleague ended up in reading a lot of his texts.

Instead of supporting him I just told everything would be fine in the end. He handed in a thesis and it was good. However, it took way too much time for everyone: him, me, my colleague.

• A grading sheet, which the students get in advance. They know how their thesis, results, final presentation and working attitude will be graded. They know that even if "the thing their supervisor imagined" did not work out because it was infeasible they can still get a good grade. In fact, I had two students with everything going wrong and still getting a 1.3 (best possible grade in Germany is 1.0). The grading sheet helps the students on setting a focus when everything fails but they want to finish, makes results comparable, etc.
• A free-style application form, where students can enter their skills without selecting a topic. Our website is not up-to-date anyway. We try to find a good match for the skills of each students. Considering that a student spends six months on a topic it should be a good match. These days, we are so overwhelmed by applications that some of them are not answered, sorry for that ;)
• A supervision agreement. This document describes supervision in both directions, i.e., what a supervisor can expect from their student and what a student can expect from their supervisor. It is somewhat specific to our group, as Max was basically asking everyone in the team what they think might be important and summarized this into this document. While it might sound very formal it helps a lot. Especially B.Sc. students who never worked for a company before have no idea what to expect at all. Most things in that document might sound quite obvious for everyone who has already supervised theses.
• Mid-term talks for M.Sc. theses. These are not graded. They are intended to provide students with early feedback not just by the PhD student supervising them but also by other students and my boss.
• Example theses. Some of our students won prizes for their thesis. While this is not the bar for a 1.0, having a few good examples helps a lot.

Except from the supervision agreement, which might differ a lot for each group, these things are relatively easy to offer.

Selecting a topic

Going back to my failures when supervising my first student, the free-style application form helps in selecting better topics. It still means that you need to adapt your research scope and not everyone has that choice. I got very decent theses out of supervising topics that were "out of scope" of my PhD and I eventually changed my scope. If your goal is not finishing your PhD within short time, go for supervising interesting topics!

Also, help the student in handling all the things that could happen during a thesis. Their thesis might not be their top priority. Know the examination rules. For example, at our university students can withdraw a thesis within 2 months if this is their first thesis attempt, and it won't count as failed thesis attempt in this case. If you feel that such rules might be relevant to the student, tell them. Always keep these deadlines in mind. And know how to extend a thesis in case something doesn't work out. Support them with all the regulations that might get in their way as soon as other things in their life become a higher priority than finishing their thesis.

I got a couple of "problematic" students and most of them did very well in the end. You might not profit from supervising these students but they will definitely profit from your support. Pick a non-perfect student from time to time if you consider expanding your soft skills not being a waste of time.

Some students already know what they want to do after their thesis. Surprisingly, many are still undecided what they want to do, even though finishing their M.Sc. is just six months in the future and they should apply for jobs soon. This problem might be specific to Germany/Europe, though, where studying is almost for free, and joining industry to pay off your student debts is not required. Ask them what they want to do after their thesis and help them in finding a good job. Tell them what typical salaries are, especially if this is their first job. We don't talk a lot about salaries in Germany...

You might not have good industry contacts when starting your PhD but your B.Sc./M.Sc. students will join industry before you have the chance to do so. Take that chance and ask them where they go and later ask them how they liked it so far. Your first generation of students might pave the way for your second generation of students. I already had the situation where a student wanted to join a company as trainee, told me about this, and I had the contacts to make it possible for her to directly join a security team without being a trainee. It can be as simple as this and still means a lot to your students.

I know that many supervisors consider this out of scope but what else is supervising a thesis about if not thinking about the next steps in life? And an academic career is not the answer to everyone.

We often team up in supervising students. I had and still have too many students. However, co-supervising a student is less work and you might still be supportive. Especially when the primary supervisor is supervising a thesis for the first time. The other way round, if you are supervising a thesis for the first time, ask a colleague if they can be a co-supervisor. And be clear about who has which priority, I definitely failed at that once.

Due to the sheer amount of students I recently started teaming up two students together for one topic. They get different tasks but would work within the same area. This definitely saves some time for me and as of now I would say it also helps the students.

Publications, thesis awards, travel grants, 🦄

Keep in mind that some students just want to write a thesis. This is fine. Publishing a paper, talking on stage, traveling abroad—this is not for everyone. Ask them if they are okay with you writing a paper about their thesis in that case.

Anyway, tell your students about these opportunities and support them. As a publication resulting from their thesis is their first paper you might be the one writing it. Also, handing in a thesis for an award means that you need to write some form of recommendation letter. At my university, we also have a lot of gender equality money that enables female* students to travel almost anywhere. Finding security bugs can also mean that students could get bug bounties. Supporting your students in these opportunities is still little effort compared to what it means to them.

My students were talking on stage, sometimes together with me, got awards for their excellent theses, publishing papers at top venues, got some bug bounties, and traveled to places like Singapore, Las Vegas, Oulu and Leipzig (yes, 36C3, not that exotic but paid by university).

If you find that great 🦄 student do whatever you can to support them. Yet, do not forget to support your weak students as well, they will need your support. You might not start with supervising 🦄 students but your supervision might also not be that great. Once you get better the applications in your inbox will get better. Still give a chance to everyone—or, if your inbox is exploding as mine, give a fair chance to random "weak" students from time to time.