Paula's anwer is very thorough but if I could just add a few remarks...
A good starting point might be to think about which course format you'd like to use. See here for information: http://docs.moodle.org/22/en/Course_formats
A clear heading and a small but attractive picture makes the site welcoming. Set up a skeleton site with just your main topic headings and then try switching between formats to see which one works best for you. Consider if the course will be used by everyone in lockstep ie all working through it week by week or topic by topic or if students will progress at their own speed.
When you say 'attractive' do you mean 'pretty' or that they should want to visit the course? A few relevant, well placed graphics will certainly help but if you want to ensure they visit the page then you have to set them tasks that require it. Are your courses going to be graded? If so you may find that a few 'participation' tasks could encourage them to visit the course page. My courses usually have something like 20% for a final exam and 80% course work. 5 or 10% of the coursework mark will be allocated to 'participation' so that i can give them review tasks and quizzes without them having a major impact on their course grade.
Anyway, good luck with your new course.