Spend on the surfaces you touch every day. Countertops, cabinet hardware, and the kitchen faucet get used dozens of times a day, and better materials there feel better and last longer.
Spend on what's hard to replace later. Flooring, tile, and plumbing locations are expensive to change once the kitchen is finished, so choose them carefully up front.
Save where it's easy to update. Paint colors, light fixtures, and even backsplash tile can be changed later without tearing out the kitchen. A simple, well-installed subway tile looks clean and timeless at a fraction of the cost of specialty tile.
And never save on installation. Even premium materials look cheap when the tile isn't level, the trim gaps at the corners, or the counters aren't supported properly. The finish work is what makes a kitchen look professional.