1. No clear goal/vision.
2. Lack of focus.
3. Unwilling to admit faults.
4. Not listening. They just keep talking, talking and talking.
5. Many young entrepreneurs are so greedy.
6. Talking talking and doing nothing.
7. Spending lots of time on developing & less time on selling.
8. Not having proper business plan.
10. No Enough Money.
11. Doing it alone. Not getting support from others.
12. Waiting too long to launch.
13. Staying in control every step of the way.
14. Raising too much money too early.
15. Keeping your idea a secret.
16. Forgetting to create a brand.
17. Being afraid that someone will steal your idea.
18. Thinking that you are your customer.
19. Trying to monetize ideas rather than monetize sales.
20. Counting your eggs before they hatch.
21.Trying to serve two kinds of customers.
22. Avoiding your customers and team.
23. Ignoring Marketing.
24. Comparing yourself to other Startups.
25. Ignoring history.
26. Avoiding thinking about revenue.
27. Using your lack of funding as an excuse.
28. Just following your passion.
29. Asking people to sign NDAs before discussing your startup.
30. Lying to yourself when things are not right.
31. Believing that hiring sales people will cure your revenue problems.
32. Postponing the calculation of your cost of user acquisition.
33. Separate business and personal finances.
34. Hope for the best result, But plan for the worst.
35. Trusting your gut, rather than getting validation for your Idea.
36. Not getting your business to market fast enough.
37. Not knowing when to pivot.
38. You take too much advice or none at all.
39. Not Marketing, No Problem.
40. Putting the customer last.
41. Making the wrong dicision on fundraising.
42. Making networking low priority.
43. Hiring the wrong people.
44. Trying to serve everyone.
45. Building without customer validation.
46. Shouting from the Rooftop.
47. You gable with things you can't afford to lose.
48. Too little, too late.
49. Poor employee quality.
50. Location, Location, Bad location.
51. Choosing a bad name.
52. Not Doing Market Research.
53. Imitating Other Businesses.
56. Quitting your job too early.
57. Expecting to be successful instantly.
58. Being driven by money alone.
59. Not adapting and Not Networking.
60. Making a Service for Everyone.
You can watch following video to know your mistakes.