Succeeding in economics as an undergraduate has a lot to do with adopting a kind of intentional myopia. You need to forget most of what you know about people and about the world. Replace the model of the universe you've constructed in your mind over the course of decades with the model or models that economists have constructed in computers and on the back of napkins in a few hours or days. As an undergraduate, you are unlikely to need to know any models that were composed on anything so advanced as a computer.
Next, take commonsense concepts that anyone with half a mind will have noticed a thousand times during life. Take the tendency of large bottles of wine to vanish almost instantly when left out at parties and call it a 'common property failure.' Take people's willingness to put their future at risk due to acts committed under the influence of excessive amounts of alcohol and call it an 'increase in the marginal rate of time preference.' Make constant references to the Prisoner's Dilemma, ideally formulating it differently each and every time.
The following words should also be used as often as possible: asymmetric and imperfect information, externalities, substitution rates, indifference points and curves, and equilibria. While all rather straightforward in concept, the use of these shibboleths will endear you to economics professors, whose entire societal value is founded on their ability to understand words that hardly anybody does. It’s also useful to employ perfectly ordinary words in a sense that implies they are somehow specially relevant to the discipline of economics; good examples are ‘signal’ and ‘incentive.’
Graphs are an excellent idea, especially for expressing concepts that could be explained with one lucid sentence or example, but which require the complex intersections of at least three or four lines (preferably coloured and with the areas between them shaded).
Unless you are a graduate student, time can be essentially ignored altogether. The reason for this has much to do with the above comment about back-of-the-napkin versus computer models. It’s a bit ironic, actually, the extent to which people get turned off economics because the models you learn at the outset are such bad representations of the world. The truth is, you probably need a PhD and a hefty amount of post-doctoral work to be able to understand a model that addresses even a moderate fraction of the complexities of human beings and the complex dynamic systems with which they interact. We can only hope that all of our static models of marginal decision-making have more than marginal usefulness.
Finally, and this is the big secret to undergraduate economics, remember to include one or two pithy observations based on your super-economical knowledge after jumping through all the hoops of explaining things in terms of the rational choices of mutually disinterested actors. You can point out that, for example, while the signaling model of education implies the absence of societal benefits to higher education, it ignores firstly the extent to which improving the signaling mechanism can further Pareto optimality by reducing information failures that prevent efficient factor utilization. Secondly, having an educated population has innumerably non-financial benefits, like people generally living more fulfilling lives and being able to participate more effectively in democracy. Pointing out that you can see where the models fail will 'signal' to your professor that the aforementioned myopia is intentional and that you can pull back the hood of economics and see the real world again.