The basics

The options open to you are going to depend on what (if anything) you're celebrating, the amount of time you have to organise your party, and the people you're going to invite.

Think where, when, numbers, food, and  - most importantly! - budget.    

If you decide to have a dinner party you're probably not going to be able to invite 50 people, so think about the premiminaries carefully - even if they seem obvious, because otherwise you could end up changing your mind and having to start from scratch again.  

Once you've got a rough idea of what shape your soirée is going to take, think up a theme. The possibilities are endless: from costumed/masked ball to karaoke kings and queens to murder mystery to Disney characters to dress for less than a fiver (charity shop chic).

A word of warning, though: make sure you choose something your guests are going to approve of - the party is for them and you want them to have a good time. If you're not sure, go for a safe option and avoid scaring your new work colleagues off by informing them they've got to come as tarts and vicars!