•Turnout. It has fallen steadily. In 2004 it was below 46 per cent, down from 65 per centin 1979. Polls suggest a majority of Europeans will once again stay away. Turnout in central and eastern Europe was much lower than in the west. The figures are distorted if other elections take place at the same time or voting is compulsory (as in Belgium and Luxembourg). Yet everywhere turnout is lower in European than national elections.

•Protest voting. Because little seems to be at stake, people often show dissatisfaction by voting against governments. The economic crisis may increase this trend. Britons have a single-party government to vote against. In Germany and Austria a grand coalition of the two big parties may drive up votes for small or fringe parties. In France the National Front has competition from half a dozen other small parties. In the Netherlands Geert Wilders’s Freedom party may do well.

•Anti-European Union votes. In Britain UKIP is distinctive in denouncing Brussels and all its works. Libertas, an umbrella group led by Ireland’s Declan Ganley, is fielding 600 candidates and may win a couple of seats. Anti-immigrant parties also campaign against the EU.

•Who will win? Proportional representation ensures that no party will gain a majority. The European People’s Party has the most seats and the Party of European Socialists is second. The EPP will probably still be the biggest group even after losing the British Conservatives (who promise to set up a rival anti-federalist centre-right group with allies mostly from central and eastern Europe), partly because it will gain recruits from Italy.

•To maximise your influence. Vote in Estonia. In 2004 it had both low turnout and a disproportionate number of seats.

•How to vote. If you are still not sure, go to www.euprofiler.eu, a website created by the European University Institute in Florence that matches your views to your country’s parties.

© The Economist Newspaper Limited 2009