I have Client and Candidate Objects seprately. Created a Job Obejct with lookup to Client. I need to create 
1. Application Obejct as Junction with many o many for Job & Candidate 
2.I need to track interview as well, its a one-one mapping for Job, Candidate or can be lined to Application Object.
  Should I create another Junction object for Inerview (Job & Candidate)?
    Interview is for a particular Application Object so can I have Interview object looking up for existing Application (Juncion Object) 
3. If interview is success , I need another Onboarding object . Its for Client Object and Interview /Candidate . Do I need another object or merge with Interview/Assignemnt based on result field.

What is best approch for data modelling. Are there any examples and guidlines I cna look for ?

hi guys,
help me out in using standard controllers in vf trailhead getting a error of
Challenge not yet complete... here's what's wrong: 
The page does not include a bound owner's email variable for the Contact record
cheers...