Hi Annia! Welcome to DC!
When I plan a menu, I think about an overall concept first which will depend on what's being celebrated and the number of guests. Is it a Spanish tapas party? Is it all Thai food? Is it mixed Asian? Is it Italian? Mediterranean? Is it a romantic dinner for two? A feast? A formal sit-down or buffet type?
And then each menu item must be something I would love to eat myself, which I think my guests will enjoy, and which I know I can make very well. (I always test new recipes out on hubby. He loves being my guinea pig.)
In deciding which particular food, I normally start first with the main course. Beef, seafood, lamb or chicken? Then I match the starch that goes with it (mashed potato, fried rice, pasta, etc.) Then I decide on what veggie side dish that would accompany both well. Then I think about what starter to put (salad or soup or appetizer) that would be a nice introduction to the meal. Then finally dessert.
I normally don't repeat herbs in any dish in the menu (to avoid taste fatigue) and I try not to repeat cooking methods across the dishes (say, only one baked item, one fried item, one sauteed item, etc.)
I try to choose dishes that can be prepared ahead of time, or that require very little final cooking/assembly before serving. THis is so I can spend time with the guests.
I also keep a file of the events I've hosted, who were present, and what I served, so that I don't repeat the food to the same guests. I've already compiled a list of successful dishes in my repertoire and I usually refer to this list when I'm planning a menu.
Hope this helps you...