An executive is a person who always decides; sometimes he decides correctly, but he always decides. (John H. Patterson)
When you're new to business there's one fact you need to know - and that is you don't know it all. If you've been in business a while, then you'll understand. It's your business and you are responsible for everything - even when you delegate the detail to a third party - be they external or internal.
That's not to discourage you - simply to point out there are so many areas to deal with you can't do it alone - at least not well. The father of business advisors, Michael Gerber points this out in "The E-Myth Revisited". And he simply focussed on internal business factors - vision, strategy, structure and culture, through the parts of the business - products and services, marketing, people, systems and finance.
Most owners recognise they need an accountant on board - but what about a lawyer, risk advisor, banker, marketer, HR advisor, etc? And that's just in general terms. Sadly most owners of small businesses take the cheapest option - DIY. And there that can usually be got away with - but the result is less than optimal for the growing business.
There are special issues facing start-ups. Costs incurred before a business starts (and that can be an interesting issue) are not deductible - but some costs are needed before you commence - or even decide it's a viable option. If you don't have a start-up fund available, perhaps you should question whether this is right for you.
You depend on advisors early on to ensure your foundation is solid. The accountant is generally the one you deal with (or should deal with) most often - but they shouldn't be relied on alone. They're not supposed to offer advice outside of their areas of expertise - although sadly some do. Their advice in such cases is probably based on experience from clients - that varies. Similarly lawyers shouldn't be relied on alone - they may miss some tax or other aspects that can lead to sub-optimal decisions - which will either cost to rectify - or come to haunt the business in the future. And the same applies to the others. They work much better together - not in each other's way - but their combined expertise ensures there is less likelihood of important things being overlooked.
This is not aiming to sell anything - our own team is only two strong. We rely on others when needed - although our work as accountants and as business development advisors gives us a broad knowledge base. But we have seen far too many businesses start with high hopes and end with disappointment. And we're not just talking complete business failure. Most businesses do survive - at least for some time. But they don't ever achieve the owner's goals and add to their life. You really don't want to end up with a business that detracts from your life - do you?