You kind of have a general idea how many you will invite. DD went to a small school and even if everyone in her class came, it would only be 70 people! We knew she would have around 100 people attending, so that is what we planned for.
DD was number 3 and a pretty smart cookie (mom brag she was valedictorian), so I wanted to do it up big for her. I started buying marked down items her freshman year. She teased me about that, but I wanted to be prepared! Her school colors were black and gold, so it was easy to pick up items on sale. We went with her high school colors because we also used all of her pictures and awards and most were black and gold to decorate the hall, so everything just flowed.
We had a hitch in our plans in that my mom developed dementia and needed to be watched the whole time, and I was in a car accident so I was in a wheelchair. Thank heavens for my DDIL and her friends because they set everything up and took it down.
We did a nacho bar. We had a hot table that included a big crock-pot with boneless, skinless chicken breasts and salsa, refried beans, tortillas and that wonderful but bad for you orange plastic cheese.
Cold table that had all the cold toppings. Lettuce, tomatoes, pico, shredded cheeses, sour cream and salsas, corn and black beans. We had a big kiddie pool on the table filled with ice and then had bowls with the toppings set inside the pool.
She didn't want a cake, so she bartered with her boss and instead of a gift, her boss baked and decorated cupcakes for the party.
For drinks we just used coolers with ice filled with sodas and water. Not what I had planned, but it was easy. We started buying soda in march when it was on sale, so we had plenty.
We also did a candy buffet. Once again, I started picking up bags after easter and then every week at the grocery so it was cheaper. I also used big bowls for things like tootsie rolls, double bubble and suckers and smaller bowls for the more expensive candy. I used corsage bags for the candy bags and they were cheap but nice looking and not so big that people took lots and lots of candy.
I had plates, napkins and silverware at each of the tables so it kept people moving. If you forgot a fork with your hot food, it was OK because you could get one at the cold food table.
We had the party at our church, so we were able to have tables set up as people came in with all of her pictures and awards. We used a classroom to eat and serve food, so we just had table decorations set up in there.
We used one of her senior pictures a friend had taken for her announcements and invites and if we mailed them, used them as a post card to save money on postage.