Apartment Hunting (Frankfurt)

I will be re-locating to Frankfurt in September and will be making a trip in early August to look for an apartment. Any specific recommendations on brokers or services as I am looking for the most efficient way to view different neighborhoods and apartments and also quickly work through a lease agreement?

In terms of additional information I am single and looking to live in a fun area that is close to lots of bars and restaurants and transit. My budget is flexible but would like to keep it around Protected content per month if possible and ideally have a Kitchen included.