Eurovision, very much like Christmas and Cliff Richard, comes but once a year. Unlike Christmas with Cliff Richard, however, the evening flies by so you owe it to yourself to do the night justice. In order to put on a decent party, I've got some fairly obvious suggestions. Enjoy Saturday.

Drink

The all important ingredient for getting the most out of the show. Without grog, you may as well spend the evening jabbing yourself in the leg with a pair of scissors...it'll be just as enjoyable.
And when it comes to booze, the more the merrier is the key. Have enough for everybody, don't run out.
It's a special occasion, so dust the cocktail shaker out, pre-buy the ingredients you need, and wow the crowd with your Cruise-like shaking.

Or you could go down the punch route, pool your resources into one big bowl of tipple that everyone can share, and call it the "European Cup" or something poor like that.
Here's a link to a website dealing with drinking games during the show. Although not ideal (if it were to be followed strictly, the amount of drink imbibed would bring on blindness) it does have some interesting ideas.

I reckon though that any serious drinking should be done during the marking stage. With 42 countries voting, this could get messy. So you could simply swig if your country gets 12 points. I reckon that a swig should be taken if your designated country is one of those three mentioned. If done properly you shouldn't be able to remember a thing in the morning.

Food

Simple one this. If you are having a soiree at home, then you can either do the usual bite-sized middle-class fare, or more adventurously do a recipe from the country hosting the event.

This year it's Helsinki which is a lot easier than recent Latvia or Ukraine. It's probably back to a basic potato-based bread/cake wiith sweet onion topping (a proven winner only because of the large amounts of booze already drunk). Alternatively you could ask Mr Sainsbury if he has any reindeer/elk hanging around on his meat counter.

Window Dressing

Flags - I've invested in 3'x5' flags of most of the Eurovision countries. These are expensive when sourced from the UK/Europe. There is though an Ebay shop based in the USA, selling them for $6 each. It mounts up if you were to get them all, but you can view the store here.
Balloons - Always go down a treat. Sexually suggestive ones even better.

Wallchart

 

I stumbled across the following wallchart from another site. This is a great example of how to involve everyone, run a book, place comments, and allocate countries for drinking purposes all-in-one.
Odds - Make sure that it's up on the wall. Be William Hill for an evening, but make sure that you don't lose too much cash. Do this by putting a cap on how much they can bet (say £1/2Euros), or on how many countries they can bet on.

Fancy Dress

A boa, a red wig, a bit of lippy, a Lou belt, a pub singing contralto, and you have guaranteed fun. Someone represented Germany in '03, can you tell from the pictures who was Lou?

How often do you get the chance to don a fake tache, and a frizzy perm. Not often I'll warrant, so make sure everyone enters into the spirit or you'll be left looking like the only butch good-time girl in the village.

Paper based Stuff

Email updates - Send occasional tit-bits of information during the build-up to the big day. It keeps the excitement up, whiles away a few minutes at work for the reader, and is just plain fun for the author.
Scoring Sheet - Make a comment sheet for guests to fill in as they go along.
Points Cards - Alternatively you can produce printed cards that can be held up with numbers 1 to 12 (excluding 9 & 11 of course). Adding them up as you go along can be done, but in practice this is tricky to manage.
Invitation - If you're going to do something properly then a proper invitation on proper paper with a proper stamp on it needs to be sent. The letter needs to set the tone.
Lyrics - Once each guest has chosen a country to represent, send them the countries lyrics a week before the event and get them to sing the song while it's on. Lots of mirth.

Others

Quiz - Just in case there's a massive yearning for it, keep a small Eurovision quiz handy, bearing in mind hardly anyone knows anything about the contest. So more than ever the focus is on light hearted nonsense (a good example being a music round of truly dire Eurovision efforts of yesteryear).
Beer Labels - Previously I have highly bizarrely manufactured some beer labels based on the acts of the years contest, stuck them on bottles of grog and handed them out. Quite weird.
A Big TV (& within the UK, access to BBC Digital)
Good friends