For a toddler you can pretty much pick a theme by anything you see your toddler taking a special liking too. If they have yet to show any real interest in one thing or another you can bet what ever you choose will go over just fine. Discuss party themes with the birthday child.
Allow them to pick a few of their favorite ideas and you throw out a few ideas. Take each idea and write them down on their own individual piece of paper or large notebook card. This is where the brainstorming comes in. You and your soon to be guest of birthday honors will have to write down on each theme what you would need for decorations, food to follow theme, cake idea, game ideas and party favors as well as where the party will be located at.
Once you get the 6 basics written down, look at each of them individually and pick out the top three themes if both of you had given three ideas. Base your decision on your budget, ease of pulling off, as well as child’s enthusiasm, within reason of course. From the top three picks, re-look at supplies needed to pull it off as well as location and see if there is anything that cannot be accommodated.
If all of them are within you budget and capability range, you can give your child one of two options; they can pick their favorite out of the three or you can throw them in a hat and let them pick that way. Once the decision is made, it needs to be final so make sure you are capable of pulling off any of the three given choices.