I've held two first birthdays, so I'll just share my opinions for you to freely ignore if they do not make sense for you!
Pick a theme that the child likes, and tell everyone who will be there, as well as those who cannot make it (people who miss the party often still like to give the little one a small gift, and feel less out of the loop if they know the theme).
Goodie bags that relate to the theme are generally given to the participating children as you are saying good-bye and they are leaving. You want to make sure to get things that will be appropriate for the child, and they can relate to your theme or just something kids in general like.
Open the gifts towards the end of the party, after the games, because the givers like to see the child actually open the thing they gave. If some small child has to leave early, you can even let the honoree open a gift early, just so the other child can watch, smile, clap, give a hug, whatever. It is interesting the joy and pride I have seen in even very little kids when they see another child open the gift they helped select.
Definitely provide a time range, and for a 1-year-old, keep it shorter. You can say something like, cookout from 2 pm to 4 pm, with the understanding that family and very close friends can stay and hang out "after the party." This way, though, parents with small kids know how long they are expected to stay, and have a definite "OK, it's over, we can leave without missing anything" expectation.
So, decorate according to your theme, even if it just involves one tablecloth. Have two or three games for the kids. There are about a zillion websites that can help guide you. Have plans for what to do if it rains. If some kids might be a little older, it is nice to have a hands-on craft for the kids who get there first to do while you wait for everyone to arrive. Can be as simple as coloring a name tag, bookmark, or other thing they can keep.
When the parents arrive (and for little kid parties, they are expected to remain with their child the entire time), tell them the schedule of events. Something like, 1 game at 2:15, cookout food until 3, birthday cake at 3, another game or 2 until 3:30, then presents, and goodie bags awarded as children leave.
Wow, did I get long-winded? I hope this helps guide you a bit.