Selling our work is the generally the number one goal of authors that publish their books but it is important to not only put it out there but also to let others know where to find it. Marketing is so important but if done incorrectly your efforts can be next to useless. You would never want to see an erotic novel on a website for children, though that is an extreme example, it can show how bad of an idea it is to simply share your work everywhere.
If you are showing your work to people with little or no interest in the genre or it is not the correct reading level, i.e. children's books on an adult site or vice versa, then it will not matter how great your sales pitch is because it will fall on deaf ears. First and foremost you have to know your audience. If you are dating someone that loves romantic comedies would you take them to a slasher flick on a romantic night out? Hopefully the answer would be no. The same goes for promoting your books. You wouldn't want to push your latest true crime novel at a romance writers convention nor would you proudly display you children's picture books at a horror conference.
Before you even hit print it is a good idea to go on to different sites like Amazon or Barnes & Nobel to see books similar to your own. Look at how the are categorized and pay attention to the other books recommended. Once you have a list of books and authors you can search on Google or social media sites to see how those works and their creators are portrayed. You can then throw in some tweaks to make the promotions your own but you will have started by understanding who it is you are selling to.
At face to face events you are not always surrounded by just your target audience. When I get a booth at a show there are bound to be hundreds if not thousands of faces walking past me and only a small percentage will stop to talk to me about my books. That is fine though because I am not trying to sell to everyone, just to those that would be interested in my genres and topics. Kids like the candy on my table and the mothers with them tend to stop and chat with me about one or more of my books so for me it is a great ploy to get people at my table but for another author I see often that wrote a based on true events book about combat neither the kids nor their moms are the right group for him. He talks to the men that show up in military hats and the bikers with flags proudly stitched onto their vests.
We do not overlap in our marketing because we have different audiences. We will however speak up if we are talking to a general book fan and mention the other author in attendance because cross promoting can help both of us. The biggest advice I can give is to make sure you do your research, not just on your book, but on who will buy it as well. That way you do not waste time and effort trying to catch the eye of the wrong people and instead can grow a true fanbase of those who will love what you created.