The best way to nudge is to simply offer your opinion. It's exactly what you said you were looking for. I think you should buy it. Lions and Sharks both nudge customers, but the key difference is when they nudge. Sharks nudge very early in the sale, even before they know if a customer likes an item.
Lions only nudge when they know the customer likes the item and it fills their needs.
Helping customers make decisions is part of the service that a great sales associate provides. Testing Role-play with another associate who will play the customer. Using a piece of merchandise from your store, present at least three features and benefits. Closing Do the same exercise again with your role-play partner. Try the Assumptive technique first, and then the Alternate close.