There is a wealth of information out there for anyone interested enough to look it up when it comes to query letters. While doing my own research I found several examples of letters but even more samples of email queries. There are of course numerous similarities between the two but there are a few differences. One of the biggest differences is how you address the letters. Being professional and using specific names is important in either letter.
It is also important to be professional when submitting in another way. While reading a blog post recently on author.pub I saw that the blogger mentioned he had a significantly better acceptance percentage when he submitted in person as opposed to through the mail or online. He noticed that when you get the chance to put a face on the project as well as pitch verbally people have a greater chance to stop and talk about your book with you.
This is the same reason I prefer selling / promoting in person. Digital may be the way of the world with a few holdouts going through snail mail but there is still nothing that compares to shaking hands, exchanging a smile while presenting not only your book but also your brand, in other words, getting the chance to sell you. Of course the next big question I can imagine is on your mind now is "If I am going to try to submission person, where do I go?"
There are different choices for that endeavor. You could choose to locate any agents or publishers that may be somewhat near you and go to their offices. Make appointments or just show up and hope they have a few moments to talk, there is always a chance that could work. I however would recommend attending conferences and conventions anytime it is possible. Agents, editors and publishers regularly attend such gatherings and are far easier to track down for a little one on one time at a location specifically set up for those types of meetings.
If you are going to attend then it is imperative that you bring copies of your manuscript with you. Make sure there are several copies and that they are edited, polished and presentable. Most will only want a partial copy of the manuscript along with your contact information so if you have business cards it would be a good idea to bring those along as well. Practice how you would present your book, your elevator pitch, but make sure you are prepared to actively discuss the story and not just sound rehearsed. For introverts this can be a scary concept but I promise you that it can lead to wonderful things if you just take the chance to present your book face to face.