Hi Sudeep,
For common integration scenarios for integration between SAP Business Suite (with a heavy focus on SAP ERP) and Ariba Network or Ariba Procure-to-Pay/Order, SAP does provide packaged best practice guides/instructions via SAP Rapid Deployment Solutions which can be downloaded for free for registered SAP customers and SAP Partners at the SAP Service Marketplace at:
https://service.sap.com/rds-cloud then navigate to Supplier and pick the appropriate package (AN or P2P) and download the content. If you have access issues, you'll need to address this with your customer's basis team members, or with your own SAP Partner advisor which Debbie also pointed you to.
You'll have prescribed integration guidance for the best integration options for the most commonly required standard SAP document types & data. A good blog from Andreas Muno can also be found here which goes into a little more detail here: http://scn.sap.com/DOC-64734 .
Hope this helps!