I'm guessing you will be reporting your income and expenses from your lawn & landscape business on your schedule C.
In order to save your accountant the most time, which in turn will save you the most money, try your best to total up your income and expenses based on the following categories from the Sch C attached below.
It is also a good idea to save those bank statements and receipts from major purchases to give to the accountant so he has some backup for the income and expenses you are claiming, which he will be signing his name on.
After getting familiar with Sch C, it would be fine if you grouped all of your expenses in an excel spreadsheet.
As others above have stated, the more time you save the accountant, usually the less it is going to cost you to have the return prepared. Because most lawn guys aren't that busy this time of year, it might be worth your effort to organize your income and expenses instead of the old shoebox method.
Most of your opportunities to save on income taxes have already expired b/c 2012 is over. Here are some opportunities that might be overlooked that are still available.
1. If you have a dedicated home office that is used solely for that purpose, you may be allowed a home office deduction.
2. The fuel used in your mowers and other equipment that is "off highway business use" is available to be claimed for a tax credit.
3. You can contribute up to $5,000 to an IRA for yourself and your spouse. There is more to this than a short post on lawnsite, but the general idea is that you have until April 15, 2013 to contribute to an IRA that is then still deductible on your 2012 tax return.
4. You can also set up an SEP-IRA plan. Again, too detailed for this post, but the basic mechanics are that you as the individual can contribute $5,000, but in addition to that $5,000, the business can contribute up to 25% of your compensation and it is deductible as a business expense.
Hope some of this helps!