How can bum / testicle / inner thigh pain from a saddle be prevented?
First, do you have cycling shorts w/ a chamois? If not, I would highly recommend them. As a note, they are your underwear (ex: do not wear undergarments and then put on the shorts). 

Second, how did you choose your saddle? Was it fitted through some type of measurement system ala bontragers inform system or specializeds BG system? How much did you spend on the saddle and was it appropriate for the style of riding you are partaking in?

Third, does your bicycle fit you properly? Have you had it fitted? 

So, there are a few points that you could answer to give me some help. I cannot recommend a saddle because everyone is different but I can recommend a brand that provides some type of measurement system for choosing your saddle. 
As well, if you are wearing cycling shorts a nice chamois butter might help with the chafing.