Click-a-clickThe easiest way of opening a file from the Finder is to double-click it. The downside of this method is that it launches the default application, often times not the one you wish to use. For instance, you wish to use PhotoShop Elements to do some image editing, but double-clicking the image file may launch Preview instead.
You do ask for the Menu, don't youAnother way is to ctrl+click on the file to pull down the floating menu, and choose your application of choice from the "Open With" submenu. I realize that the submenu may be a little slow at showing up especially when the file is supported by a large array of applications.
Drag 'n drop it!This is the no-nonsense method to open a file in a target application of your choice. Just click and drag the file over the application icon and release it, much like the way you drag and drop a file to the Trash. The application icon can be sitting on the Dock, on the desktop, or in the Finder; in each case, this method works just fine.
Although you may not need all three methods as often in your daily Mac-ing hours, I am sure there will be at least one that you find most convenient to work with. Hope this plethora of tricks will speed up your computing efficiency in a small but significant way.