Some things to keep in mind regarding an appeal is that the appeals officer is there to make a determination based on the strengths of a case and the potential for litigation going forward.
If you have put off representation prior to your appeal, you should retain a tax attorney. The reason for my suggestion is because this is the step before filing a tax court petition. You must be able to bring up the legal and procedural reasons for why you should prevail with an emphasis on the potential for tax litigation if you should not prevail. CPA’s and Enrolled agents can represent you in the appeal but most are not certified to practice before the tax court and they may not properly be able to preserve all of your issues to appeal.
When preparing the appeal you should carefully examine your ability to pay and your assets for equity. Find relevant collection statutes, treasury regulations and look at the Internal Revenue Manuel (IRM).
You should review how the IRS assesses your income. Do they give you properly allowances for necessary expenses? You should be aware of how they value your assets. Do they reduce the equity for some items such as personal vehicles, bank accounts, etc? How do they value business related equipment, valuables and other assets? Do they use a quick sale valuation? (Typically 80% of fair market value)