Would you rather host a shower in your home, or at a restaurant/event space? I've attended both kinds and have thrown both kinds and I can tell you what I've learned. Hosting in your home is more intimate, usually, and gives you more control. Hosting at a restaurant gives you less control, but is much easier. (Someone's done all the cleaning for you.) Here's some tips I've learned to make a home-thrown shower the best possible shower for guests, guest-of-honor, and you.
The food: Plan the menu accordingly. Are you going to do appetizers before hand? Finger foods and crudites on tables for guests to pick on? Are you doing hot food? Cold food? For an afternoon shower an easy and crowd-pleasing menu includes a pasta salad, some stuffed breads or quiches, and an assortment of gourmet sandwiches. Also, put the dessert out so people can see what's in store: Cake, cookies, brownies, cupcakes?
Seating layout: Where are people going to sit, mingle, and eat? It can be the hardest thing to figure out. Where are you going to put the food, where are you going to set up the coffee and dessert station? Where is the bride or mom-to-be going to open gifts?
Hire a helper: It took me a few parties to realize the value of this. You can either go through a service, hire a high-school kid (maybe a babysitter you trust), or ask a waitress at your favorite restaurant. Having someone to keep things clean during the party, and especially help clean up after makes the party even fun for you!
The most important thing you can do is plan and prepare--down to what types of napkins you're going to use, and what party store you're going to go to to get them. It's the best advice I can give. Oh, that and have fun! Guests follow the host's cue, so be sure to have fun and mingle with your guests!
Have you hosted a shower? What's your best tip?