There are a number of issues with this design - the color scheme is harsh, the spacing inside that yellow text box is odd, and the text at the bottom is difficult to read on a busy background, despite the inclusion of an outline on the text and copious drop shadows everywhere. I address all these concerns in the redesign, but for this post I'm going to focus on those drop shadows.
I've been doing print design long enough to remember the days when there was some work involved to add a drop shadow to an element. One of the nice things about modern design software is how easy it is to apply effects like drop shadows on the fly. But to paraphrase Jurassic Park, novice designers may be so infatuated with what they can do that they don't think about or learn what they should do.
Let's start from the top of the design and look at the three drop shadows applied.
There's now only a drop shadow on the top left logo so it stands out better from the busy background below it, and a drop shadow on the text box and image to give a little depth. Spacing and font weights have been adjusted, the busy background image has been replaced with a solid background and an image of people enjoying a previous trip, which is stronger than generic clip art. I also modified the color scheme. I let the globe image set the color palette - the blue, warm yellow, and light green are all pulled from that image, so the colors are bright and bold, but harmonious and softened from the original.