If you guys do use a CPA, remind them of their ethics training when you drop off your papers. It doesn't take a CPA to find lots of special deductions, just most people encourage their accountants to do creative bookkeeping to save them money. There are certain limits you can stay under to avoid setting off most manual reviews/requests for supporting documents when claiming deductions, and most CPAs know this. They also know which types of deductions the IRS will be auditing extra hard for that tax year (lower limits then usual.)
Remember, the IRS is very similar to Google. You can blackhat your own taxes, but if you get caught for a manual review, its not going to end well most times. If you want to be honest and legitimate, tell your CPA straight up. Some of them do creative bookkeeping on their own to try to keep you as a long term client. If your tax return is much different than previous years, ask the CPA to explain to you WHY it was that way. Then do research on your own to make sure it looks legit to you.
If something goes wrong, the CPA knows what to tell the IRS to remove all blame from himself and place it on you. Many CPAs have it set up where it basically says they take no responsibility for the accuracy of the return as they just used information given by you and took you at your word. I forget exactly how its worded, but it basically says the CPA was not required to see supporting documents regarding your claims and therefore all responsibility for the accuracy falls on you.
Just be careful guys. There are whitehat and blackhat CPAs. Make it clear you have a lot of expenses you hope are legal deductions, but you only want to claim them if they are 100% legit.
If your accountant doesn't demand to see every receipt or ask what exactly you used something for in detail, and doesn't ask to see your previous years return if you are a new client, start getting suspicious. Hopefully some others can chime in with what I missed.