If you go to their web page ahead of time, you can sign up for the IKEA FAMILY program which gets you a few additional discounts & perks.
http://info.ikea-usa.com/FAMILY/?src=ikea_web
The first time I went was a little overwhelming. At my store (and I think most), the top level is the show room. If you are buying furniture & bigger things you'll need to write down the numbers about where the actual units are downstairs. Downstairs is the Marketplace that has tons of things for sale - from spoons, cups, linens, picture frames, etc. And then after you get through the Marketplace is the warehouse area where you pick up all the larger items. You'll need to know what aisle & bin the items are located in. Then you go through to the register area. The scratch & dent section is usually right before the registers.
Have fun!