SIZE:

First off, depending on the amount of friends you have your going to need to decide just how big your LAN is going to be. I’ve hosted a multitude of LAN’s all of whcih presented new problems. My personal residence can support about 10-15 people with out blowing a breaker or worse yet, running out of room.

WANT MORE PEOPLE!?!?!
OFFER A COMPETITION/TOURNAMENT WITH AN AWESOME PRIZE(this could be covered by an entry fee)

Consider a Venue:

Got something HUGE planned? Plenty of churches, community halls, public areas, are willing to Host Events, like this for free or a nominally small fee. Now I am not saying you have to go all out “BLIZZCON” but people want to feel at home in their natural geek environment.

The Equipment:

Now for my Smaller personal LAN’s (10-15 people) I got myself a Switch(base100) which can support up to 24 people. I own small wireless router(base100)because the less cabling i have to do the better. I personally HATE cables. but the speed really cant be beat. RJ-45 cables are a MUST for any LAN party. they are beating life blood because not every geek can afford wireless N. Although it may seem 2nd nature to you, MAKE SURE THEY HAVE NIC CARDS OR ON BOARD RJ-45 PORTS. this may be their first LAN and have no EFFing clue what to do.

If your really serious and gonna host A GRAND SLAM LAN with 50-200 people. GET YOURSELF A DEDICATED SERVER. This will avoid confusion and help speed things along. Test the Game server BEFORE you start the LAN. the last thing you want to is download the software and then not know what the hell your doing.

Power equipment:

Before you go and trip a breaker or Blow a Fuse and possibly ruin a bunch of people’s PCs. You should make sure people bring Power strips with a GROUND, power surge protector. As for personal expenses Buy  yourself a fuse if you have a fuse box, and a few extra power strips for those select few who are less fortunate.

Seating:
In my basement their is elbow room for 11. with a squeeze 15. A decent 5-6 foot table will defiantly hold 2 people. and 3 if your set-up is minimal and your cables are long enough. my folding table cost me about 20 bucks its 6 feet long and is the easiest thing to bring with me to a LAN.
Chairs– have people bring folding chairs or something just as easily portable. Like a mentioned earlier BLIZZCON give you comfortable ROLLY chairs. considering you didn’t make a small mountain of gold sucking the life outta people this is not viable. Folding chairs are the way to go double so with local store for around a 25 per 3 cheap chairs.

Planning:

Have events Planned! having people haphazardly create fames is confusing and at times EFFing annoying. Plan out events to be played and have them planned accordingly for the number of people you have. For longer events try to get them OUTSIDE!

FOOD:

Three things to remember about food.
money, amount, timing.

MONEY– figuring out how much your gonna need is gonna be a hard time: Get people to pitch in. Keep track of who put in what. and give accordingly. Perhaps You could buy pizza and sell parts of it for money. BUT MAKE SURE TO TELL PEOPLE AHEAD OF TIME! *beware of the moocher*

AMOUNT – With no way to figure out just how many people will show up your gonna have to over compensate. cause having hungry gamers is a curse.

Timing – Clearly post break, lunch and dinner times so people aren’t left outta the loop.

Get a Date: and by that I mean The day your planning to HOST this shindig. Make sure you post it EVERYWHERE. and if you have to cancel POST this in TWICE as many places.

Sponsorship:
some companies are willing to drop a few goodies if your lan is of considerable size.  look further into this.

A few more tips:
Make sure you have all the latest maps, mods and patches to make sure you get the optimum experience.

Get the room ready the night before.Set up chairs, tables and trash cans.Prepare a sign-in sheet, and have assigned IP addresses next to each name. (assigned IPs are unnecessary if you are running a DHCP server)Print out hand-outs welcoming the guests and describing some rules and guidelines.Set up and connect your networks and servers, and test away(lol shop joke).