You do need a lawyer and a good accountant that knows non-profit tax law

Actually, you can live without the lawyer if you have a good accountant.  We were held up for over 6 months trying to get a 501c3 by lawyers that did not understand the process.  Finally, I filled out the forms online with the help of an accounting friend and we had the 501c3 in a few weeks. 

Non profit tax law changes each year but you can master the basics pretty easily. Also, laws change from state to state.  You need to be able to bounce ideas off of a good accountant. Many peole will approach you with ideas to "partner" meaning promote their business. Usually, this is a big no-no. As a non profit we are under more scrutiny than a for profit. Plus, you owe your donors a clear mission. They want to know that if they donate money, it is going to help needy people and not to promote someone's business.

Track all goods that leave your location We have paper checkout forms that then get entered into Excel. Every toothbrush that has been given out since we started is on record. You will need these types of documents for many reasons including dealing with taxes. We also use them for marketing. You need to know how many people you helped and what you actually got out the door.

Track every penny that comes in or out on paper We currently use Quickbooks and it is great.  We had volunteer financial help for years but now pay a CPA to keep up the books.  From the very begining, save every receipt and track every expense. Do monthly reports for the board too so everyone is very clear of the money trail. This will build the atmosphere of trust needed for success.

Hiring staff: If you pay staff you do need some really good training or a consultant to help you with HR law.  In Massachusetts this is pretty complicated and I rely heavily on our board for help.

Each year until you generate $250,000 you need a finacial review which cost about $3,000 here and must be done by an independent consultant.  You need this to get your 990 forms and to get any grant funding.  Formal financial reports and key to getting grants and keeping in check with the IRS.

Once you exceed $250,000 (currently) you  need a full audit. Our's currently runs $7,000 and is a significant expense.