Hi, Chris!
This is a great question!
I think the answer is a two-parter. Because you've listed your question in the category "First Disney Vacation," I'm going to suggest that you consider a bit of both!
I've really liked the convenience of doing a little research on Walt Disney World's website for reservations. This allows me to take my time and research dining options, resort amenities, proximity to a certain park or Downtown Disney. Knowledge is power, so nose around the site to get an idea of costs, as well.
If you need a link to Walt Disney World's website, I've included it here.
At that point, if you are unsure of something (i.e. Is there ever an offer of free a Dining Plan sometime near when I'd like to travel? Are there any renovations scheduled for the pool at the resort I'm thinking of booking, which might affect my vacation?) then you can call (407) 939-6244 to ask a Cast Member for specifics.
When I help family and friends find options for their trips, I always begin on the Walt Disney World website. Because everything you need to compare options is there, it's a great tool to get started at your own leisurely pace. Again, being new to this, you might then want to double-check your choices with a Cast Member, who might also have a few very helpful suggestions.
Please send any additional questions you may have regarding your upcoming trip! I'd love to help!