Start with a clear and clean coffee table. That's the easy part right?!
I would bet money that every decorator and designer out there will tell you a coffee table needs a good book, or several. Depending on how large your table is, you will want to have at least one stack of books and often more. Books are timeless investments and it's always fun to open one you have not looked at for years. I love to go to Half Price Books, here in Dallas, and stock up on piles of great hard backed books. I really recommend hard backed books in general when you purchase something you want to keep for any length of time. Find books that you love and start with the largest on the bottom and have all the books facing the same direction going up. I started with a simple stack of equal sized books.
Once you have placed your books in a nice spot on the table, I recommend adding a plant or flowers. It's so nice to have greenery in your home and it adds texture and color to your table. Being able to switch things up occasionally also keeps it interesting. I love going to Trader Joe's for fabulous deals on fresh flowers and succulents that don't break the bank. If you don't want to purchase live greenery, consider a really good looking faux plant. I have seen fabulous faux succulents, orchids and plants lately. I even have a great faux plant from IKEA in my home that was under $10!
Once you have stacked your books, you'll want something decorative to place on top. If you have a very large table with several stacks, you do not need something on each pile. My rule of thumb is to use odd numbers, so if you have 2 stacks, be sure at least one pile has a decorative object. If you have 3 piles, maybe two stacks have something on top. Consider the height of the books and the line of sight beyond your table when choosing items (ie...you don't want something too tall on front of a TV). I love placing a box on top of a stack of books so I can keep a deck of cards, or miscellaneous items that always need a home. Like this Big Happy Buddha that obviously needed a home with me.
I design for real life, and almost all my clients have a TV and/or Audio system with remote controls, so I like to have a place to keep remotes handy. A tray is one of the easiest ways to hold a remote and you can also place a set of coasters or another decorative object to add a little interest. I found this fun brass hand to hold my remote. I added a small box and a fun wishbone to have an odd number of items and make the space balanced. People love the wishbone :) And don't be afraid to play with placement a few times like I did!