What are the challenges that I should be looking at ?

There doesn't seem to be an easy way to really answer such a question. What a place pays depends on the business, there is no set amount. And I don't know if one can even generalize that the pay will be more in bigger cites - or at least in comparison to the costs that tend to be more than in smaller communities. But one can say that a city with a few million people like Munich will have thousands of restaurants compared to a village that might have just a few.

But there will be a wide range of situations. The higher paid jobs will be at the more expensive, exclusive, successful places. You won't find a grill selling sausages and french fries paying a great amount. But then workers with good credentials will also be competing for these jobs. I would think you should look for places that fit to what you can offer. Your profile says you are from India, thus Indian or international restaurants are probably a better fit than German but then again you have been here for a few years so maybe you've learned German cooking well. But say a Chinese or Italian restaurant would not seem to be a likely opportunity except as a helper if you haven't had some years of experience focused on those cuisines.

I would suggest you investigate cities with some proximity like Ulm and Augsburg to see if you like them and if you find opportunities. If not then you can look farther and included bigger places like Stuttgart and Munich.