Several factors can influence how much you want to charge for a ticket.

You may want to see if there are other comparable tickets available for sale and see how those are listed. This will help you price your tickets competitively.

Some sellers have unrealistic expectations and will set a price far higher than market value which often results in the lack of a sale. Listings that are priced reasonably or below market value will sell quickly.

Note that all fixed priced listings currently active on viagogo have NOT sold and are merely the seller's "asking" price.

Keep the 10% service fee and tax on the fee in mind when setting your price.

Make sure that you understand any regulations from the event organiser that might limit the amount for which you can sell tickets.

If you set a price and later change your mind, you can always go back and change it under My Account which is always available from the top of your browser window, as long as they have not been purchased.