Accountant
Gorms
If you are setting up and running a limited company it is better to hire an accountant at the beginning. His / her fee at the end of the year should include on going advice. There is a lot of form filling, including setting yourself up as an employee, PRSI, schedule for salary payments, low salary and dividend at year end vs standard salary and surplus retained in company and subject to CGT.
Setting up as a Sole Trader is more straightforward, and you can find all the relevant records to keep/ expenses you can claim etc in any 'Start Your Own Business' book.
Many of these records also apply to a limited company i.e Sales book, Purchase book, list of cheques used, list of debtors and creditors.
As you say, the more detailed and straightforward your records, the cheaper the accountants fee will be. You can do all the work yourself, but it can be quite laborious if you are not used to it, and is therefore better (for the head anyway) to get a professional to do it for you. Shop around and do a deal. Try the smaller firms. I always found that it it much cheaper to hire an accountant outside of, or on the periphery of Dublin e.g Bray (or any large urban area for that matter). Remember you will mainly be communicating by phone, email or post, and will only have to visit perhaps once a year.
Regards