Here is an ingenious (in my view) scheme of my own invention which I tried successfully in several courses and intend to use it this time. The starting point is: 30% weekly quizzes + 40% weekly hw + 30% final. However: each individual quiz or hw score which is below than or equal to (percentage-wise) your score on the final will be dropped - together with its weight! E.g.: if all your hw scores are above and all quizzes below your score on the final, then your total score is composed of 50% hw and 50% final. Thus, there are many reasons why you want to take quizzes and do hw (as well as many other exercises, not assigned as hw); yet a particular quiz/hw score can only improve your overall performance, but can never hurt your ultimate result compared to the final exam. In our time of many uncertainties this might be particularly useful: if for whatever reason you cannot come to a quiz or are not ready to submit a hw, you should not fret over this -- my policy does not penalize you for skipping it.
Besides, I don't have a preconceived distribution of As,Bs,..., and will be happy to give everyone an A should everyone learn the material well (for which I hope very much, especislly that the subject is interesting and simple). What exactly it means to learn well will become clear after some quizzes.
Thus, the general idea is that you don't compete with each other, but rather strive to learn the material the best you can. Respectively, collaboration and/or use of outside sources are not prohibited (tests excluded). Yet, each instance of this should be explicitly acknowledged in your homework. Failure to acknowledge one's use of somebody else's ideas is commonly known as academic plagiarism. So, let's practice the right ethics.