One thing that will inevitably come as you continue to do your design work is the craving to speed up simple tasks. You'll begin to notice that you spend quite a bit of time continually have to find and click on the features you want. Now, many people who have used Inventor for a couple of years will know many of the basic shortcuts - but many more will never take the time to set up custom shortcut commands.
Inventor gives you the option to set up nearly any command or feature with a keyboard shortcut. You can get there by finding and clicking the Customize button Inside of your Options Panel in the Tool ribbon.
Now, it's worth it to take a couple of minutes and figure out the commands you really use the most often before presetting anything. These will be the commands you probably want to start with. I really recommend many of the sketch commands, for example nearly any command under the Create Panel, Modify Panel, or Constrain Panel.
Once you have a few features that you'd like to set up as a shortcut, you can sort by Categories and select the category of commands that you'd like to apply a shortcut to. In this case, lets select Sketch. You'll see that it filters out every other command except for those which are used during sketch creation.
At this point, it's time to start setting up our commands. Now there's a couple of ways that we can do this. Inventor allows us to use Key combinations such as "Ctrl+" or "Shft+" type commands, or sequential keystrokes such as "CN", which I use for the Construction command, or "CV" which I use for my Vertical Constraint Command. If you would like to use sequential keystrokes, understand that your aren't limited by length, you can even type out the full name of the command if you'd like (but I wouldn't...we're trying for speed here!). You should try to keep it short and sweet.
Because I spent a lot of my time doing design work, I made sure I set up and test a lot of these commands - and I do recommend thoroughly testing them. These shortcuts need to be easy to input and remember (i.e. something you can quickly build into your repertoire). I would almost never need to click up in the Feature Ribbon after I set these up, my left hand would quickly input the shortcuts while my right hand did all of the drawing. My personal recommendation when inputting commands, is to use two sequential keys and use the first letter as the panel your pulling from. Here are a couple of examples: "MT" for Trim (under our Modify Panel), "CC" for Circular Constraint (under our Constrain Panel), and "CRC" for Center-Point Rectangle (under our Create Panel).
I highly recommend you set up shortcuts for nearly every constraint and modify command.
Understand that these options are limitless! Just remember to, again, test these items out - you'll likely have to change them once or twice to find something you really like.