Take a photograph of the blank canvas before you paint a single section. That is the most useful trick on this page, and almost nobody does it. Once a number is covered you cannot read it, and sooner or later you will paint over one you had not finished, or lose track of which of two near-identical grays belongs where. A photograph on your phone solves it permanently.
The rest of these are the things regular painters work out after three or four canvases. None of them require buying anything, with one exception noted at the end.
Before you start

Let the canvas settle
A canvas that shipped rolled will want to curl back. Unroll it, lay it face up on a flat surface and weight the corners with books overnight. It will lie flat by morning. Do not iron it and do not take a blade to a crease, both of which are suggested online and both of which ruin canvases.
Set the light before the paint
Most of the frustration people report with numbered canvases is really an eyesight problem in disguise. A lamp positioned to the side, rather than overhead behind you, throws no shadow from your own hand across the section you are working on. This costs nothing and fixes more complaints than any technique.
Decide where your hand will rest
Work from the top down, and from one side to the other, so your painting hand never rests on a section you finished ten minutes ago. If you are right-handed that means top-left toward bottom-right. Left-handed, reverse it. Keep a sheet of clean paper under your hand as insurance.
While you paint
Finish one color completely before opening the next
Work through every section carrying the same number, then move on. It saves washing the brush constantly, keeps the color consistent across the whole canvas, and gives you visible progress, which is most of the pleasure of this. Jumping between colors is how a canvas ends up half-finished in a cupboard.
Light colors first is the forgiving order
Dark acrylic will cover a light color that has strayed over a line in one coat. Light acrylic will not cover dark, no matter how many coats you give it. Painting the pale sections first keeps your mistakes fixable.
Experienced painters often do the opposite, laying in the darks first to establish contrast. That is a reasonable choice if you are confident. If you are not, go light to dark.
Two thin coats, never one thick one
The number showing through is the most common complaint on any numbered canvas, and the instinct is to load the brush and bury it. Do not. Thick acrylic dries as a visible ridge that catches the light forever, and it stays soft underneath for days.
Let the first coat dry properly and go over it again. Whites, creams and yellows almost always need the second pass. What you should not do is mix white into a color to make it more opaque, which is advice you will see repeated: it changes the color, and the section will no longer match its neighbors.
One drop of water, not two
If the paint has gone stiff, stir in a single drop of water at a time until it moves off the brush cleanly. Overshoot and it goes transparent, and transparent paint will not cover a printed number however patient you are.
Do not stand your brush in a jar of water
It bends the bristles permanently against the bottom of the jar and lets water into the ferrule, which is what makes a brush shed hairs later. Keep a damp cloth or sponge on the table, wipe the brush on that between colors, and lay it down flat.
Keep the pots closed
Acrylic skins over in an open pot faster than you would think. Close the lid every time you set it down, even if you are coming back in five minutes. If a pot has already skinned, lift the skin off in one piece rather than stirring it in, or you will be painting with lumps for the rest of the canvas.
Small sections
Outline, then fill
For any section bigger than a fingernail, paint the boundary first with the tip of the brush, then fill the middle with the side of it. Trying to fill and edge in the same stroke is what produces wobbly outlines.
Load less paint than feels right
A brush carrying too much paint floods over the line before you have any control of it. For small sections you want barely enough to wet the tip.
Mark the tiny ones in pencil
Where two sections are so small that the number is hard to make out, write the number larger in the margin with an arrow, or lightly pencil it somewhere it will be painted over. Doing this for a whole cluster at once, before you pick up a brush, is much quicker than squinting at each one mid-session.
When something goes wrong
You painted the wrong color into a section
Let it dry completely, then paint the correct color over the top. If the wrong color was darker, expect two or three coats. Do not try to wipe wet acrylic off a printed canvas, which smears it into the neighboring sections and can lift the printing.
A color is running out
Stop and take stock rather than pressing on. Find every remaining section that needs it and work out whether you have enough. Thin the paint very slightly and use it sparingly on the smallest sections first.
If it does run out, most kits have no replacement available, which is worth checking before you buy. Every one of our designs has a matching full replacement paint set, and on a custom canvas you can add spare sets at checkout rather than hunting for them later.
Two wet colors have bled into each other
Let both dry, then re-cut the boundary by painting the lighter color back up to the line, then the darker one over it. The fix is nearly invisible. Preventing it is simpler: give a section ten minutes before painting its neighbor.
Save a little of everything
Keep a small amount of each color back until the whole canvas is done. At the end, go over it in good light and touch up the thin patches and the ragged edges. Twenty minutes here makes more difference to the finished result than any amount of care earlier on.
The one thing worth buying
A magnifier lamp. A combined light and lens on an arm costs very little and transforms the experience if the small numbers are what frustrates you. Twelve of our own reviewers mention faint or tiny numbering, more than mention any other single thing, and this is the answer to it.
The other answer is to size up. A 16 x 20 has larger sections than a 12 x 16 of the same design, and it is the simplest fix of all.
Going beyond the numbers
The sections are a floor, not a ceiling. Once a canvas is filled, you can soften the boundary between two adjacent colors with a barely damp brush while both are still wet, which turns a flat, posterized look into something that reads as a painting. Skies and water benefit most. Try it on a small area first, because blending across a numbered canvas costs time and is genuinely optional.
Adding a highlight the kit did not ask for, a brighter edge on a lit surface or a darker accent in a shadow, is the other easy improvement. Neither requires new paint.
What we actually put in the box
Since specifications get invented online, here is ours plainly. Pre-primed cotton canvas, not board and not foam, shipped rolled in a tube so it arrives without creases. Acrylic paints, vacuum-sealed so they have not dried on the shelf. Brushes in a range of sizes. An 11 x 17 reference print, so you are working from something you can actually see rather than a thumbnail on the packaging. The framed sizes include a small easel.
the techniques that actually help is what to do with all of it once the box is open.
If a pot has thickened anyway, what actually works is a drop of water, and what does not work is nearly everything else people suggest.
The phrase itself is ambiguous, and what online paint by number actually means separates the kit you receive from the software you do not.
There are 39 designs, all licensed original artwork, plus custom canvases from your own photograph. You can see everything in the full collection, and if this is your first canvas, start with the beginner's guide.