If there will be other young kids, keep the party short--an hour or two is plenty.
If you want to decorate with balloons, opt for the silver helium-filled kind. Latex balloons are a choking hazard to kids under the age of 4.
If you're serving food, do yourself a favor and don't try to make everything. For instance, bake the cake but buy deli sandwiches. Or grill burgers and have a bakery do the cake.
Take pictures of the cake and of baby in his birthday outfit before the guests arrive.
Don't force baby to be social. With all the attention, your little one may need to retreat for a bit.
Consider hiring a sitter or asking a young relative to stay with the birthday baby when he needs a break.
Consider doing the fun part the night before. Strip baby down to a diaper and let her experience her first piece of cake. Then, if he's too thrown off during the party to enjoy the "real" cake, you won't feel disappointed.

Birthday Party Theme Ideas for a First Birthday Party
By Ellen Neuborne @ www.americanbaby.com

Hard to believe it's been a year! And so much has changed. Your enthralling and mysterious infant is now sitting, crawling, maybe even walking and full of personality. As the big Oh-One approaches, your family may begin to ask what you've got planned for the festivities. Keep in mind the tender age of the guest of honor and any similarly sized guests who may attend. Stick with familiar situations and themes to avoid an unintended fright.

Fireman First Birthday Party

Many a baby loves the big red noisy fire truck and will thrill to see a birthday bash in this theme. A firefighter party is easy to put together. And firefighters appeal to a broad age range, so this is a good pick for a party that will have older siblings in attendance.

Fire Hat   /  Plastic Fireman's Hat

Party favor: Red plastic firefighter hats.
New plastic fire hat is priced right for those little firefighters.

Fire Truck Sipper Cup

Use these Pails And Shovel instead of traditional loot bags. Fill with Stickers, Beach Ball, or Yellow Squirt Ducks.

Game: Firefighter's Parade. In addition to rushing to fires, fire trucks are known to roll through town in holiday parades. Enlist the parents and older kids to don fire hats, ring bells, and toot horns for a firefighter's parade. It can be around the block or around the living room, depending on your guests' enthusiasm.

Party Favor: Magnet picture frames, suitable for use on a refrigerator or other first birthday Party Favors

Making a Band Party
Be sure to invite the neighbors -- this party is a noisy one! Babies love to make music and you can plan a party around that activity that'll be a blast. To make sure everyone has fun, have duplicates of some favorite instruments, such as drums, tambourines, and maracas. Use caution if instruments have small parts.

Giggle Rattle

Maracas Sweet Lullabies CD Kids Sing-A-Long CD

Tambourines Boys Party Music CD

Party favor: Musical instruments. Keep it simple. A maraca or bell or mini drum works just fine. So long as it can stand up to a good banging from baby. You could even use sturdy plastic First Birthday Fun Plates

Game: Music performance. Get your future rock stars out into the middle of the room. Put on some Party Music and encourage the little ones to play along. Pick some  favorite Party Music for the background so kids will recognize it and want to join in. 

Kids Sing-A-Long CD

First Birthday Party Queen for a Day

This makes a good choice for an event where many of the guests will be too tiny to truly party. The mood will be festive and the party favors fun, but the little ones won't have to do much more than sit around and be cute.

Cake: Make your own princess Castle Cake

Party Favor: Picture frame. Loot Bag Treats

Game: Photo opportunity wearing robe and crown. Use a Polaroid instant camera and set up a "throne" in a safe, comfy easy chair. Use this Fairy Princess Hat or Happy Birthday Tiara to capture a Kodak moment of the princess and her court.

Pink 1st Birthday Frame
Rainbow Number 1 Candle

Sesame Street First 1st Birthday Party

Sesame Street

Cookie Monster Balloon

An easy baby/toddler favorite. Sesame Street provides baby's first celebrities, and a party devoted to Elmo and friends is sure to be a hit. Place a "Welcome to Sesame Street" banner on your front door and have the birthday boy or girl wear a Sesame 1st Bib and you're good to go.

Party Favor: Elmo and other character stickers. Look for big stickers that make a big impression (use stickers with caution).

Elmo Blowouts
Sesame Street Mini Dot Stickers

Game: Sesame Street sing-along. Switch on the VCR or fire up the CD player and encourage big and small party-goers to belt out their favorite Sesame Street tunes. Set aside Sesame 1st Birthday Treats for the adult who has best command of Sesame Street lyrics.

First Birthday Party Planning Timeline:

One month before first birthday party day:
Make guest list, plan menu, send invitations.

Create your own invitations:
Blue Photo Invitations
Pink Photo Invitations
Pink Gingham Invitations

Two weeks before first birthday party day:
Shop for:

1st Birthday Party supplies
Stickers
Party Favors

Decide on a First Birthday Cake and purchase cake supplies.

Ask a friend or relative who has RSVP'd to act as your assistant on party day.

One week before first birthday party day:
Shop for First Birthday Gifts
Get Favors bags ready.

Day of Party

Hang Birthday Banner and Foil Balloons
Set the table
Pick up cake if you ordered a custom cake
Let the birthday boy or girl have a nap
Set out appetizers or snacks
Enjoy a stress-free party!