Anyone with experience in dealing packages held in Customs Office?

I ordered a few items worth 550 USD in total via Fedex. Fedex usually deals with import tax VAT etc and bill me during delivery but this time they have informed that I have to go personally to Customs Office to pay tax.

Dealing with customs office sounds extremely daunting. Does anyone know what the process is, the dos and donts so that I am not looted by Dalals and customs officers?