Such good advice from so many people!
Congratulations on your decision to take the leap! There is no better feeling of accomplishment than planning and opening your own place. To be your own boss and celebrate your own victorys is a wonderful feeling. That being said, it is definately hard work - and lots of it.
A solid business plan is so important. The financials have to be well thought out. Once you have thought them out - subtract half the sales, and add on twice the expenses. If you can still make it add up, you're on the right track.
A big difference will be had depending on wether you buy an existing place, or start from scratch. There are certainly pluses and minuses to each way. If you are going to start from scratch and build out - do your homework! Codes and permits, restrictions and zoning issues should be well researched prior to choosing a location. If your buying an existing business, that legwork may already be started for you - but double check everything. Location, Location, Location - it's importance cant be stressed enough.
Make due on the bare minimum to start. Buy only what you absolutely need to get your business off the ground. Once your up and rolling, you can continue to invest in your business. So much of the opening expense can get tied up in what you "want" rather than what you "need".
Don't stretch yourself too thin. You can't do it all yourself - even if you are a control freak. You will burn out. It is so important to hire key staff that you can train and trust so that you can get away from the place once in a while. After two years, I can finally walk away for a weekend with confidence and know my staff has it handled. I probably could have, and should have done it sooner, but the control freak in me wouldn't let me. I definately have my hand on everything being done in my restaurant, but I also have key people in charge of both FOH and BOH. This is the only way you will have time to do the things an owner must do as well.
Hire a qualified Accountant. If cooking is your forte - not accounting, hire someone who knows the ropes. They can handle the taxes, payroll, monthly books or other things that they are trained to handle. Nothing is worse than getting a call from the IRS because you forgot to file some quarterly report. Most new business owners are not experts in this feild, so hire someone who is. THey can also help you get your Busines identity set up and make sure you are protected should the unexpected happen.
Have realistic expectations. So many others have commented on the financial expectation. They are right on. Staying in the black during your first year is very difficult to do. Many, Many unexpected things will come up, and you may find yourself without a paycheck. Be prepared for this, and have plenty of resources to cover yourself should this happen. Stressing about finances will take over your world if you let it.
Enjoy yourself. In everything you do, find joy. This will be the biggest rollercoaster ride you have ever taken! There will be days when your want to poke your eyes out, tear your hair out and hide in a closet and scream. There will be other days when you cant stop smiling about what you have accomplished, the rush you pulled off without a hitch and the adoration from your customers makes your head swell. Take the good days with the bad and know they will even themselves out in the end. Put the time into your decision to make sure your family can handle life without you. You will be married to your place for quite a while - and the honeymoon is several weeks of stress. Soon enough, the place will get on an even keel, and you might even start enjoying it.
Being an Owner, after so many years of working for someone else has been my greatest joy. It tears my heart out to be walking away from my business so early in the game, but health issues in our family make it impossible for me to do anything else. I envy your enthusiasm as you get started on your trek - there is truly no better feeling. Good luck to you!