In order to help you, out, it would help if you could tell us what you have tried already and what results you had, good or bad. As it is, we dont know what you have already thought or tried!
Assuming that you are in the business of organising, managing and/or hosting parties, then I would think that one of your strongest promotional tools will be the parties themselves. I suggest that you put thought into how you brand yourself at these events, so that anyone attending will be in no doubt as to who organised it. Word of mouth is a powerful thing.
If you can't be explicit with your branding and contact details then consider unobstrusive branding of printed menus etc. Also, a memorable name that can be easily searched upon, on the Internet, would be a bonus.
I have a website and then had some advertising done in specialist magazines
I think to reiterate what others here have said, before anyone here can really help you, you need to go into much more detail about what you are doing, what you have tried, who your target market are?
A website in itself is not much of an advert, it is more of a shop window, but is a pretty useless means of advertising unless you are driving relevant traffic to it.
You say "party business", party plan? Organising raves? If you can put a bit more in to what you are looking for, then the help on this forum will be a lot more forthcoming.