Getting into the country is easy, so long as you have the right documentation. Immigration channels at airports are divided between EU and non-EU passport holders. The former usually results in a cursory glance at your passport, while visitors in the latter category are scrutinised a little more.
Ireland has a two-tier customs system: one for goods bought duty-free outside the European Union (EU); the other for goods bought in another EU country where tax and duty is paid. There is technically no limit to the amount of goods transportable within the EU, but customs will use certain guidelines to distinguish personal use from commercial purpose.
For duty-free goods from outside the EU, limits include 200 cigarettes, 1L of spirits or 2L of wine, 60mL of perfume and 250mL of eau de toilette.
Amounts that officially constitute personal use include 3200 cigarettes (or 400 cigarillos, 200 cigars or 3kg of tobacco) and either 10L of spirits, 20L of fortified wine, 60L of sparkling wine, 90L of still wine or 110L of beer.
Not required for citizens of Australia, New Zealand, the USA or Canada, or citizens of European nations that belong to the European Economic Area (EEA).
If you're an EEA national, you don't need a visa to visit (or work in) the Republic of Ireland. Citizens of Australia, Canada, New Zealand, South Africa and the US can visit Ireland for up to three months without a visa. They are not allowed to work unless sponsored by an employer. To stay longer in the Republic, contact the local garda station or the Garda National Immigration Bureau.
Although you don’t need an onward or return ticket to enter Ireland, it could help if there’s any doubt that you have sufficient funds to support yourself while in Dublin.