The command name
The command names lack a bit of creativity. The more plane and simple the command names the better. A range of fantasy names may seem very exiting but are hard to remember. And you don't want to consult a guide every time you want to use that particular command of which you remember what it did but forgot the name of.
A short keyboard entry
The commands are in the first place created to safe time. Most experienced software users will agree, a key combination or shortcut increases the work pace. That's why the commands are activated by a letter and, a few, with a number combination. If a shortcut for a command is a combination of 5 letters or more it's not a shortcut anymore. So a limited amount of key combinations is required. The combination of letters is an extraction from the command name. And if you compare the shortcuts you will see there's a relation between them. For instance the shortcuts for randomisers, commands that execute and action with some sort of random result, all end on RA for random. Elevation commands end on IE which stands for In Elevation. That way you don't have to remember the shortcut for each and every command but you can this logic to recall the combination.
With most commands you need to make a selection. In most cases that's the first thing you need to do. Most commands are created in such a way that the action it will do for you can be applied to multiple entities at once. So you don't have to individually select each and every entity but you can select them all at once. To make your life even easier the command will filter your selection. If you use a command for which you need to select lines the command will look only for lines. If there's no line in your selection set the command will not continue.
To get you started all variables the command relies on have preset values. They are based on your drawing units. Those values are related to generate a nice result instantly. When you change a variable the command will check if that's a valid value. If you need to set a distance for instance and enter 0.0 as value the command will not accept it. It will enable you to play around with the settings without going wrong. As soon as you enter a valid value for a variable the command will accept it and remember it. So the next time you use the command in the same session you don't have to set all those variables again.
The main menu
The main menu is your control centre. From here you can change all possible settings of the command. In de command line you see which settings you can change. For AutoCAD versions up until AutoCAD 2012 you have to type the letter that is in capital for that setting. For instance, if you want to change the Distance, you will have to type a 'd' or a 'D' and you will be able to change it. For 'Yes/No' settings like Align you will only have to type an 'a' or 'A'. You will stay in the main menu but the command will toggle the align setting from yes to no or vice versa. From AutoCAD 2013 it's also possible to click the variables in the menu.