Here are some silly medieval costume tips, which were originally written in relation to a banquet I was running. I took these offline but I had a request for them so thought I'd publish them again. Enjoy!
We'll start with some very basic tips for those in an extreme hurry, and then move on to the more complicated stuff.
The easiest costume in the world: get a rectangle of some material, cut a hole in the middle, put your head through the hole so you have one half of the rectangle in front of you, the other behind you. Hey ho - instant tabard! Add a belt to keep it in place, add some jewellery, wear plain black underneath (not jeans if you can help it) and there you go. Highly recommended.
Ladies: do you have a long floaty dress? Any elegant vaguely dark-ages looking jewellery? You may be in business already... Similarly, cleavage-enhancing tops are always a safe bet, especially if you're going for the "witch" or "wench" looks. Having said that, we're not sexist, tabards as described above are fine on ladies, as is full plate armour - hey, we're not going to argue.
Jewellery can really help liven up your costume - big brooches on cloaks, large chunky necklaces, anklets, bracelets, etc. will all set you out as a Lord or Lady of style and taste. Anything medieval-looking will do, really. If you want to go buy something, Past Times has a pretty good selection of this kind of stuff, for example.
Costume hire shops are cool but bear in mind that you may well get food/drink on it, which might end up costing you. Your call.
Need to know more? Well, here are a couple of costume guides written by real enthusiasts. These are taken from "The Daily Grail", the annual magazine of the Cardiff Arthurian Society, which was the student society that got me into banquets in the first place.
The 1996 Costume Guide - I'm pretty sure this is by the excellent Mr Andrew Craze who, if he makes it to the banquet, will make the rest of us look like the curtain-wearing charlatans we really are. :-)
And here's another great guide from Mr Craze (from the 1997 Daily Grail, I believe). No pictures but the descriptions and tips are excellent - so it's not to be missed.
A Beginner's Guide is an A-Z of costume elements, and as such is probably of more interest to the hardcore banqueteer.