Keep receipts, bank statements, and canceled checks to support your claimed tax deductions. The IRS may ask for proof. If you don't have these documents, a tax attorney can help rebuild your records. They can assist in proving your deductions are valid.

The most likely way to trigger an IRS audit is to not accurately report all your income. 

There are certainly other common triggers: suspicious math, unusual deductions (for your income or business), and a pattern of losses in your small business, which might more resemble a hobby to the IRS.

However, the most common trigger to an audit is not reporting all of your income.

An IRS audit is no small inconvenience. It’s a tedious undertaking, and penalties for underpaying taxes can be severe. You could face a 20 percent penalty for negligence or understating your tax liability. A 75 percent penalty applies for fraudulent underpayments. You must prove that your underpayments were not fraud. Interest charges may even apply from the due date until you pay. These can add up. Serious tax evasion can lead to heavy fines, asset loss, and even jail time.