The things to 'not give up on' and really pay attention to are Layers - very very important, the difference between 'paper' and 'plot' spaces and in the recent versions you have 'layouts' which are also a very important thing to grasp in order to print (known as 'plotting' from the old days of pen roller plotters) your work in meaningful ways.
One of the golden rules of doing work in any CAD package is to not waste time re-drawing what someone else has already done - for example, if you were designing a house and wanted to have a picture of a sofa in the lounge, then rather than spend ages designing the sofa, you google up any of the hundreds of 'CAD Cafes', find a sofa, download it then insert it into your house.
Also to think about is the notion of scale - autocad will default to either metric or imperial units depending on what is in settings, but everything is based on units of 1 - it's up to you to decide whether that's 1 micron, 1 metre or 1 mile. Generally speaking, most people will draw in millimetres for the kind of stuff we do, so if you are importing bits of someone elses work (known as 'blocks' [more recently as 'xrefs' - Xternal REFerence]) then you have to know whether you need to multiply or divide by 10 / 100 / 1000 etc in order for it to make sense. For example, if you drew a house where 1 screen unit = 1m, and then wanted to insert a table from somewhere else into the kitchen, then that table probably got drawn with 1 screen unit = 1 mm - so you need to apply a scale factor of .001 (ie, divide by 1000).
