I was very suprised to find that many reviewers were saying how hard it is to gain one star, and to make famous friends. Just make sure your sim is all greened up when they head to stuido town, and since the first few levels don't require skill, it should be easy! As for getting famous friends, find a sim who has a lower or about the same star level as you. Talk to them, compliment them, whatever, just get a few social points. Then head home and invite them downtown! We all know it doesn't take much to make friends there. In no time you'll have famous friends and some star levels. Once you get to the more advance photo shoot, and from that point, don't make the same mistake I did at first. They'll give you 3 ways to do the shoot (or song, or soap opera, whatever). Randomely pick one way, and choose it three times (you dont have to find the sequence the three go in like I thought). The director will either have you in a thought bubble or you in a thought bubble with an X through your sim. Use these indicators to switch what you need to. You get three tries, so it isn't too bad. Just make sure in between visits to studio town you work on charisma and creativity. Use a piano for creativity because they'll gain fun at the same time. Overall, this is more challenging then the previous expansions (and makin magic) but if you work at it, it's quite fun!
p.s. if your sim is good friends with a celeb, go into the celeb trailer, and invite that person in, and see what happens ;)!