Great customer service professionals have mastered the art of providing support while also selling to the customer. This often requires going beyond just answering the customer's question.
Did the customer ask about an item's availability, but it is out of stock?
Send the customer a link to a similar in-stock item.
Send the customer directions for joining the Business Partner's newsletter, so they are kept up to date on arrivals.
Think the customer would be happier with a different item?
Take the time to recommend the alternative to them. Maybe there are different colors, cuts, prints, patterns, sizes, etc.
When suggesting items/alternatives to a customer, limit the choices you provide to the best 3. Providing more than this can cause decision fatigue: the customer may just give up on ordering all together.
Are there parts or accessories that would be useful to the customer?
Include those in your response.
For example, if the customer is asking about a TV to mount, take the time to also send them links to the TV mounts that are offered.
Did the customer fail to provide you enough information to provide suggestions?
Feel free to ask them for more details. Ask them what they are looking for or what things they like so you can better assist them.
This also involves using all of your resources to your advantage. In this case, your resources are knowledge and policies.
For example, If the customer is concerned about sizes, make sure they have the sizing guide, recommend a size to them (when possible,) and remind them of any return policies just in case it doesn't work out.
If the customer is concerned about making sure they get the best deal, remind them of any price match policies or other guarantees. If the customer wants to cancel an order because of price changes or newly developed concerns, it could be helpful to remind them of policies to put them at ease.
Lastly, one of the best tools you have at helping sell to a customer are personal anecdotes. Tell the customer about your experience with the brand, a similar item, or a similar situation to help build rapport.
Oh, and don't forget that you often have the customer's entire order/subscription history available to you! Take the time to review this information to make sure you're not recommending products that the customer has already purchased. These details can also help you in determining the customer's style or preferences for any recommendation you might make.