How to prepare yourself to do startup

1. Search new business opportunities constantly
2. Improve Technical Skills and open new business opportunity in new Tech Space
3. Build networks. Keep meeting people on local entrepreneurship meetups & other events. You never know who among those will give you the lifeline at the right time. Also, you need to build connections with useful contacts.
4. Learn sales & marketing. Your startup's future depends on it. You have to learn ESPECIALLY if you are an engineer. You just can't think that you will hire someone who will automagically sell stuff for you.
5. Mentally prepare yourself and your spouse (if you are married) to look for the long term gains to overlook the short-term pains. The spouse needs to be strong to enable you to run your business.
6. Cut spending to a bare-minimum. Learn how to live frugally (even if you don't want to start living like that right now). In a startup life, a lot of times you have to figure out ways to cut down spending, to improve your survival rate. Learn how you can do that now. If you have figured how to live 12-18 months without a paycheck, you are on your way.
7. Build your savings. The one who has gold in his pockets sets the rules, in a startup.
8. Figure out the top 5 things you want to do in your life and do it NOW (if you can). In a startup life, you won't have time to do them. By doing them before, you will have less regrets starting up on your own. You can always convince yourself that you did those things that many of your peers (who are still making that hefty salary) have not done.
9. Watch inspiring movies. I watched the entire list here: AFI's 100 Years...100 Cheers. When you watch movies such as Stand & Deliver or Life is Beautiful, you get a different perspective in life. This will be really helpful when you are under pain and just want to give up (this situation is more likely than you imagine).
10. Do something adventurous (such as hike the Grand canyon from north to south side, a 5-day camping in Central America or volunteering in Africa). You will learn teamwork, withstanding pain and taking the right level of risks. I know many who use their hiking/camping lessons in startups.
11. Meet family, friends and attend parties. After you start up, you will get in your bunker and meet people only when they can generate a business lead. You won't have any time for personal life in the first 2 years.
12. Ask yourself if you are really in it for the money. If yes, you will be disappointed as statistically you will make a lot less than what you could in a big corp. On the other hand, if you are in it for creativity, satisfaction and adventure, you will be able to withstand the long pause without funding. Don't brag about anything, "..Do it for your own satisfaction . It is important you do it straight off your heart you don't talk about it."  - Mukesh Ambani