My advice:

Start small. You can easily expand but it’s best not to do too much too soon before you understand gardening and the level of upkeep (and money) you are willing to commit.

Pay attention to sun/shade and water needs. Also be mindful of spacing. Lack of circulation opens plants up to disease.

Plant what you see thriving in your neighborhood.

Leave space for annuals. Your perennials will not always be in bloom and will not look fabulous in every season. Make space for annuals that you can pop in for each season.

Don’t over mulch. Piling mulch up against shrubs will kill him. Don’t be heavy handed and please don’t create mulch volcanoes around your trees. Covering the bark is bad and trees will die if roots are smothered.

Lawn or garden?

You could start with a landscape designer and get plans drawn up, and then work them gradually, maybe even over years. Usually you would start with hardscaping (walls, patios, walkways, decks, fire pits, raised vegetable beds, etc), then trees and large shrubs, then foundation beds and turf or turf substitute, then perennials, then annuals.

Start a notebook and make a note of how you want to use each part of your yard. To be seen and not touched? For kids to play? To entertain guests? Veggie garden? Herbs and cut flowers? To do hobbies? To lounge quietly with a book or a drink? Pets? Color scheme? Make a note of views from various parts of the house. Block it, and think of each part separately, but make sure it all fits together, much like you would your interior design.

Do some research and decide your personal landscape philosophy and feel: formal and high maintenance? All native low maintenance, no chemicals? Mix of formal and informal? 70% native biomass, plus favored non-invasive ornamentals? Wile-life friendly? Anything you need to avoid like plants that deer or rabbits love to eat?

Know the growing zone you are in and pay attention to that when you buy plants. Also know how much sun each part of your yard gets per day and how the soil is in each part (dry, wet, loamy, sandy, clay, rocky)? This is important so you can put the right plant in the right place for it to survive and thrive.

Other ways to get started: walk your neighborhood for a year and snap photos of plants you like that are doing well in your area. Keep track of the seasons and what is featured in the landscape each season (don't forget winter interest and evergreens). Visit botanic gardens in the area and note plants you like and their seasons of interest.

Have fun and keep in mind that a garden is always a work in progress, ever changing.

Our builder gutted our backyard when they built our house. I'm trying to look on the bright side that it means I have a complete blank slate, but I have no idea where to start. We've planted a few trees to try to replace what was lost, and now I'm interested in planning out my yard further. I have no experience here, just an appreciation for plants and flowers and a desire to contribute to the beauty of my neighborhood. Is it as simple as going to American Plant and asking for help, or is it easier to work through my lawn service (who also planted our trees)? I'm also enjoying reading this forum and soaking up everyone's wisdom. Many thanks!