Being a successful entrepreneur can be assimilated to a carefully crafted balancing act. There is a constant influx of opposing forces that battle for your attention and being able to come up with the winning combination is what matters in the end.
The most important forces antagonizing with each other are without a doubt planning and execution. The SBA offers advice on developing your business plan; info here. On one side, you want to have a well thought out plan where the main risks are minimized and that hopefully includes a "B plan". On the other side, you realize that if a plan does not bring in any revenue until it is being executed. Deciding when to execute your plan can be daunting. However, a general rule of thumb is that planning has to give way to execution when the marginal benefit of extra planning is outweighed by the marginal risk of delaying execution.
In other words, when you think that devoting more time to planning is simply hurting the potential of the current plan from being executed, you have reached the tipping point. Remember that you can always change your plan as it is being executed, being able to pivot quickly during execution is far more important than having all corners rounded off from the start.
Another example that is often overlooked by starting entrepreneurs is the kind of office environment they want to develop their business ideas in. There is the traditional office space environment where you go into a regular lease for a space you will be alone in, have to furnish and take care of its maintenance. Another option is avoiding an office space altogether and working from home or from a coffee shop. However, there is a new trend developing in the "executive office space" umbrella; companies like Officelist offer a wide variety of shared and furnished office space for rent where you have access to the same services and amenities as a large corporation, like conference rooms, office equipment, and a full administrative staff. Since you are sharing the same space with other entrepreneurs, you will have a dynamic environment to bounce your ideas with peers and maybe even find new sources of business. There can also be a significant economical benefit since you will pay one single bill every month (all-inclusive) and take advantage from sharing resources with a large pool of companies who understand what it takes to bring ideas to life.
Entrepreneurship is part science and part art. Keeping your eyes open for opportunities and getting the balancing act under control is what will keep you moving in the right direction.