It can take a lot of tweaking to get a grid that you’re happy with. This nytimes article does a pretty good job of introducing some of the ideas behind where they should go.

Placing black squares is an art form for larger grids. Select the square and hit ‘.’ or type any letter to toggle it back. You can create a black square by typing the ‘.’ key on your keyboard or hitting the all black key on the keyboard if you’re on a mobile device. You can also use any other word you like even if it’s not in the list - it’s all COVFEFE. You shouldn’t rely exclusively on the autofiller - the wordlist(s) beside the grid give you other options for the currently selected entry. As you type you’ll notice the Crosshare autofiller magically fills in the rest of the grid. Filling the gridĪfter launching the constructor, click anywhere in the grid and start typing your first fill entry. Mini puzzles are a great way to get started because you don’t need to worry so much about the grid layout - you just need to focus on getting fill you like and coming up with fun clues. When you first launch the constructor, Crosshare defaults you to a 5x5 mini grid (to create a different sized puzzle click on “More” in the top bar and then click “New Puzzle”).

Don’t be intimidated! Constructing great crosswords takes a lot of practice, but it’s easy to get started.

Best free online crossword maker