So, you think a co-founder could be helpful on your journey? Well, first off, here are some things you should know before talking to potential co-founders:

Knowledge, Time and Money are important factors when choosing a co-founder. But in my own experience, how well you vibe is most important. Of course, it should be someone you feel like working with in the long-term. Don't make a co-founder decision just so you can, for example, get a developer for the very near future. Most preferably it should be someone, where you think: "OMG, this guy is amazing".

Regarding Knowledge: It's helpful (but not required) if you and your co-founders knowledge is complimentary. If your co-founder is just a copy of yourself, one of you guys is not really needed on the team.

Regarding Time: Personally, I currently have a co-founder who has less time that he can invest, than I do. This often happens, if one of you still has to work a regular job. But you should make sure, that your partner can invest enough time, so that it makes sense that you work together and so that you yourself feel comfortable with the situation. 

Regarding Money: You should at least talk to your potential co-founder about this topic, because it will show how much runway the person has. This means, how long the person can support himself financially without any income. Also it's important to check whether you and your potential co-founder have a synergy when it comes to handling money. If your co-founder has a lot of loans and can't handle money very well, this could very easily become a problem in your new business partnership. 

Having said all of that, here are my top picks for finding a co-founder: 

https://www.indiehackers.com/g... (English, international)
- https://www.founderio.com/de (Mostly German-speaking)
https://www.startupschool.org/ by YCombinator (English, international)
https://www.reddit.com/r/cofou... (English, international)