I'm not an expert on costuming, but the biggest things to avoid are jeans and sneakers. Black or brown sneakers aren't too bad, but white shoes really stand out. Another thing I've seen a lot of people do (and I did at my first couple events) is get a cheap leather jacket from a thrift store for some extra armor points. It almost always looks really bad, but with some creative use of scissors and a little bit of sewing, you can turn the right ugly leather jacket into a badass doublet.
If it's at all possible, you should have someone who has made at least a few weapons help you make your first weapon. The instructions are all there in the rulebook, but first-hand experience goes a long way. Here's some general advice, though:
For a staff, you probably want to use 3/4" PVC pipe. It'll be a little heavy, but not ridiculously so.
The first thing you want to do is figure out where you want to place the foam on your staff.
These are the dimensions I would use. The PVC core is 5 feet long - that way, you can get two staves out of a 10' length of PVC.
It's not required, but I like to use double-sided duct tape to attach the foam to the PVC. It tends to make weapons last just a little longer. It also cuts down on the amount of tape you have to use to anchor the foam on each end, which tends to look ugly. You can also use spray glue or contact cement to do this, but I don't have much experience with that.
3/4" PVC is a little tricky in that the 5/8" thick 3/4" pipe foam isn't actually large enough and 1" pipe foam is too large. If you get 1" foam, you'll have to carefully cut a thin section of the foam (lengthwise) to make it fit. If you get 3/4" foam, you'll have to take a long thin section (or several short sections) from another piece of foam to fill in the gap - this isn't the best method, but it's not unsafe. Make sure you have the foam extend 1 inch beyond the PVC.
Most people like to put the crush tip under the main layer of duct tape, but I like to do it over the top. The crush tip is one of the most likely things to break and this makes it easier to do repairs.
When you're putting the duct tape on, don't press it down on one end and flatten it across. You'll get wrinkles and bubbles and it'll look bad unless you're extremely careful about it. Instead, take one edge of the duct tape and lightly press it down on the foam from one end to the other. Then, starting in the center and working outward, use the duct tape roll to roll the tape down onto the foam.
That same advice applies to just about any weapon. Short swords are pretty easy to make - for those, I'd use 1/2" SDR-11 CPVC (it'll seem way too bendy when you see it in the store, but it's stiff enough for short weapons) and 1/2" diameter 5/8" pipe foam. You won't have to worry about trimming the foam down for this size, thankfully, and a pair of short swords work pretty well if you want to use two weapons. That said, if you're feeling a little more confident in your weapon-making abilities or you get them from someone else, most weapons that aren't swords look cooler than swords. :thumbsup:
As for buying weapons, it depends on your area. If you're going to play at SoMN or Chicago, I can make you some weapons -
this is some of my most recent work. Something like one of those would cost more, but basic weapons are pretty cheap.