Fill, line and colour shortcuts in Layout by Zaweba
The fill and line proxy at the top of the Tools panel in Layout by Zaweba, and the single keys that swap, reset and apply colour while you work.

Fill and line are the two colours every frame and shape carries, and Layout by Zaweba puts them at the top of the Tools panel as a small proxy: two overlapping squares, one for the inside colour and one for the outline. Whichever is in front is the one your next colour choice will change. Once that clicks, colour work becomes a lot quicker.
The proxy comes with a handful of single key shortcuts. They're small, but you'll use them dozens of times on every job.
The keys worth learning first
X brings fill or line to the front. If you click a swatch and the outline changes when you wanted the inside, press X and click again.
Shift+X swaps them, so the fill colour becomes the line colour and the other way round. That's handy when you've drawn a coloured box and decide it should be an outline instead.
D gives the defaults: no fill and a 1 pt black line. It's a fast way to get a shape back to a plain, known state after a run of experiments.
The comma, full stop and slash keys apply the last colour, a gradient or none to whichever of fill or line is in front. Slash for none is the one you'll reach for most, for taking the outline off a picture frame or clearing a fill.
Frame or text
J makes formatting affect the frame or its text. With a text frame selected, the same fill and line settings could mean the frame's background and border, or the colour of the letters inside it. J flips between the two, and the proxy shows which you're working on.
This is the source of a classic puzzle: you select a text frame, click red, and the box turns red rather than the words. Press J, click red again, and the text changes instead.
Switching selection tools
Shift+A switches between Selection and Direct selection. Selection works on whole frames; Direct selection works on what's inside them or on individual points of a path. Being able to swap without moving to the Tools panel keeps your hand on the keyboard while the other hand stays on the mouse.
Putting the shortcuts together
A common sequence for a picture frame with a thin keyline might go like this. Select the frame, press X until the line is in front, pick a dark swatch, then set the weight. If you then decide the keyline should go, press slash. If the picture inside needs moving, Shift+A to Direct selection and drag.
For a coloured panel behind text, select the frame, make sure J is set to the frame, bring fill to the front and choose a swatch. Then press J to switch to the text and choose a contrasting colour for the words.
Where these shortcuts trip people up
The proxy remembers what was in front. If you set the line last time, the next swatch click changes the line again. Glance at the proxy before you click.
The comma key applies the last colour you used, not a favourite. If you've just used a different swatch somewhere else, that is the one it applies.
And D resets both fill and line at once, so don't press it on a carefully coloured frame unless that's what you want; undo will bring it back if you do.
These few keys in Layout by Zaweba save more time than almost any feature you'd find in a menu, simply because colour is applied so often.