If the builder did not add a layer of topsoil, your first task is to add topsoil. This is easy to do, but not DIY, since the topsoil needs to be brought by trucks and spread with heavy equipment.
Once the topsoil is in place, you should add a lawn, if anything, to avoid erosion of the soil. You can hire a company to hydroseed, but this is an easy DIY project: just buy grass seed and bales of hay. Follow the instructions of the seed supplier.
Unless you are an experienced gardener or a landscape architect, it's really hard to predict how you will use your yard. Once you have developed a healthy lawn, take a look at the natural paths people use in your yard, and that's where you will place pavers. Look at areas where you'd like some privacy, and add evergreens there. Pay attention to the sun, and place plants accordingly -- some plants need full sun, some partial sun, some shadow, etc. It's all about planning. A $70 bush only costs $2 if you buy it small and then wait 2 years for it to grow. So you can spend $500 in plants and materials today and 5 years later have a $25,000 landscaping.