well you just need to see how much food are you offering ((Menu Items)) and how deep you want to get into it ((Breakfast, lunch, dinner, late night))
I'm a chef worked in the biz for 14 years so I know all the ins an outs of of this thing
and myself is looking to do something on my own the onlything I dont have the green to make the seen, so if you have any questions or anything please let me know I will be more then happy to help

1) Do you have a location in mind? If so you will need to know how much your rent per. mo. is and determine how many months you should have in reserves to pay the rent.
2) figure out additional bills like utilities. Food cost's, insurances,and deposit's for these things. Then figure out how much food you need to sell per day to pay your bills to see if you can even attempt this venture.
3) Depending on the space you lease it may or may not be ready for you to open so you might need to remodel. If so you need to go throught the propper chanels such as the City for a Tenant Improvement permit as well as the Health Department for approval.You will need to find An Architect to provide the drawings that are accepted by the city. This all cost's anywhere from $6.00 to $11.00 per square foot of your space.
4) You would then need to hire a contractor to build out your space so that it is to code.
5) Once that is done you will need to purchase all of the kitchen equipment that you need for your type of food. Keep in mind tables, chairs, forks, spoons, cups, ect..
6) You may or may not need a large sign for your restaurant.
7) Printing menu's
8) You may or may not need a menu board.
9) Advertizing very important.
10) All the misc. stuff to decorate and create your vibe so that your restaurant has style.
I hope this list helps. Good Luck