Try not to do too much because sometimes the kids get so worked up, they have a tougher day! You want to impress upon them that they are so ready for this new adventure and it will be fun, growing up is cool, etc.
Go easy on the new outfit because sometimes they get crayon or glue on it and get all stressed out about ruining something. Most kids like to wear sneakers so they can run around at recess. They need to be comfortable, not stylish.
If it's full day kindergarten, have a snack or two in addition to the regular lunch. I think a lunch from home is much easier - familiar food, no navigating the lunch line, and all that. Too much for the first few weeks. Be sure to include protein, not just carbs and sugar, and use containers the child can open on his own.
Just take a picture on the first day - maybe on the way out the door and another at the bus stop or in the line of cars if you drive him. Honestly, if you make too much of a big deal of it, they don't want to go back on the third or fourth day when you're done doing special things!
A lot of people take a picture on the first day every year and then do a collage for 13 years - that's if the teenager allows you to take pics! But at least if you do them through Grade 6, it makes a nice memento. Some people do a circle of photos and put the most recent or the kindergarten photo in the center. You can buy special pre-cut mats for these things in photo stores or craft stores.
If you're a scrapbooker, you can do a page with the photo, the teacher assignment sheet (listing the teacher's name and room number), or the bus tag (our schools give out tags to attach to the backpack to help the aides get the right kids on the right buses), and a few little embellishments or stickers.