1). If you don't remember anything else, remember this...... the party should revolve around the person you're throwing the party for! When thinking about anything regarding this party, I should ask myself (or even better, ask Molly) would Molly like this?
2). Assuming it's not a surprise party, plan a lunch or evening together with you guest of honor and ask them what they envision for their celebration? If they seem awkward, or don't know how to answer this question, here are some good ice breakers.
What are your favorite colors ?
If it's a bridal shower, ask if they would like the same colors/theme as their wedding (they may want something different).
If it's a baby shower, ask the parents if they have a color scheme/theme for the nursery, and by all means ask them what they need for the new home/baby/nursery ect...
My own bridal shower was a surprise and although I like surprises, I would have enjoyed having more of a say in my shower. My mom picked a lingerie shower theme, and quite honestly, I prefer picking my own lingerie, and I would have enjoyed a different theme. It ended up feeling a little more like a bachelorette party than a bridal shower.
3). Take the persons style and personality into consideration.
Molly is a romantic that likes antiques and vintage. She's the type who would enjoy a High Tea, or maybe even a garden brunch, with pastel flowers and embroidered linens. She's also a bit introverted so having a big bash with bright colors and a ton of guests with loud music would not be comfortable, or enjoyable for her. She would also probably prefer craft activities as opposed to games at her shower. Make sure you think about these things, they're what makes the difference between a bad hostess, and a great hostess. The more fun your guest of honor has, and the more memorable it is (for the right reasons), the closer you get to the "Hostess Hall of Fame :)
4). Ask them what their favorite foods, or at least their favorite type of food is. First take into consideration any dietary restrictions or allergies. If your guest of honor is a vegetarian, don't have a BBQ. Again, remember that there is a reason they're called the guest of honor. It's all about them :) And for the love of all that is good and Holy, ask them what kind of cake or dessert they want. They may not even like cake, they may prefer pie, or an Ice Cream Sundae bar.
5). Make sure you understand how little, or how much your guest of honor would like to be involved. Some people would prefer to just let you plan the whole thing. They may not be comfortable, or may be too busy to do much beyond that first meeting or lunch. On the other hand, they may want to have their hand in all the details. If that's the case, just breathe and remind yourself, it's all about them ;)
I hope this has helped any of you who might be throwing a celebration for a loved one. It's a true honor to be able to host a celebration for them. They will carry your generosity and the memories of their celebration for the rest of their lives. Being a good hostess boils down to this, people are happy, well fed, and well entertained while under your care, so smile, and let the celebrations begin.