Generally, one can promote and sell his or her books personally or at events. Promoting or selling a book can be done nowadays in events like comic cons.
Trying to keep your costs down when joining this kind of even, especially if you are still starting, is the first thing you should do, and one way is to get the cheapest table you can get hold on. Sharing a table with another author interested to sell his or her works is also another way.
When you have already established yourself as an author, there are ways to maximize you sales.
The number one thing you can do is to have a one-sentence pitch that summarizes up your book. Even if your plot is complicated, it is best that you do not confuse people with it.
If you can make some noise, then make that as your move. Having an aggressive personality would be an advantage, and one way is standing in front of your display and put the book directly in the hands of people and make some interesting remarks about it.
The next thing on how to sell more of your books is by drawing people with your irresistible offer, and for those will not so sales-oriented personality, you can give away pens, bookmarks, and so on, unless you have a free print to give away. As you offer something for free, it is best that you are their eye level, standing and not sitting behind your table.
Another pointer to get more sales is to have only one book that you are pushing. Note that the more items you are offering, the more distractions are challenging your buyers.
To upsell is another idea to sell more books, and you can do this by offering a good amount for people buying more than one book or a bundle of the book that you are pushing.
Another thing you can do is to promote your appearance at the event and have fun while getting many interests of your books. The time at the event can also be your promotional period, where you can talk about your book to your fans, to media people and to your potential fans. Go ahead smile and have even if your sales have not yet reached your target or if foot traffic is low, because people have the tendency to buy from those who are smiling rather than those who are grumbling behind their desks.
Fun places like comic cons are the best time to dress up as your favorite character in the book you are selling, and this is another way to invite potential fans and buyers of your books, just limit your attire to a positive one.