New to SSRS and how most people implement (on its' own server or with db engine)

HiI have implemented SSRS on one of our test servers that also has the database engine installed. This is the first time our company is going to use SSRS. What I would like some input on is: Should SSRS be on its own server for production and if not how do you handle all the http (ie do you have Report Services installed on all your servers? Do each of these server have a separate http?) Any input on how you implement Report Services would be helpful.Thanks