Paint the ceiling first. Work top down.
The brush should be small and you should tape the ceiling to protect it but otherwise the brush doesn't matter much.
wall color
Ceiling paint is a type of paint specifically designed for painting ceilings. It is different from regular wall paint in that it is formulated to be splatter-resistant, have better coverage, and be less prone to dripping. Additionally, ceiling paint is often formulated to be thicker in consistency to help prevent drips and spatters while painting overhead.
Here's a clue - why do you think it's called "ceiling paint"
ceiling because you wil be less likely to damage the walls as you are puting it up.
The ceiling.
I do it first, before painting the wall, with a sash brush, very carefully at the top. The bottom doesn't matter too much as I yet have to paint the wall, but I usually feather it out over 2-3 inches.
I've been a painting contractor for 32 years. Here's how you do it: you're going to need two coats of paint at least. For the first coat, roll your paint parallel to the ceiling to within a couple of inches of the ceiling, then using an angle cut brush of 2 to 2 1/2 inches in width (spend some money and get a good brush; don't use a piece of crap) paint up to within 1/8 to 1/4 inch of the ceiling. I like moving from right to left and painting from left to right into the paint(always paint into the paint you've brushed on the wall, not away from it). When you come back to do your second coat it will be easier to cut a line right at the ceiling because your brush slips more smoothly over the fresh first coat. The difference in color between the wall and the ceiling will make it easier for your eye to tell your hand where to go with the paint. Unless there is a perfectly sharp corner at the ceiling your line will be either on the wall or on the ceiling. In general, it's better to get it more on the ceiling than on the wall, because otherwise, assuming the ceiling is lighter, the line of your new paint will look more uneven from a distance.
To fix peeling wall paint, you should first scrape off the loose paint, sand the area smooth, clean the surface, apply a primer, and then repaint the wall with a fresh coat of paint.
It's a big job, but you can use a putty knife to get the loose paint off then 'rough sand' the rest of the ceiling and paint. Be sure the ceiling is even and if there are any dents from the paint peeling then you'll have to plaster those first, then 'rough sand.'
It's easier if you paint around doors and windows and top and bottom of walls first.
When you’re working on a home painting project, one of the most common questions is whether you should paint the baseboards or the walls first. Many painters recommend starting with the walls before moving on to the baseboards. The main reason is efficiency: Painting the walls first allows you to cover larger areas without the worry of accidentally painting over the trim, which makes it easier to clean up later. It’s easy to cut into the wall along the ceiling and corners, so it’s a good idea to cut them first to make sure they’re even, even after they’re done. Once the walls are finished and completely dry, you can move on to the baseboards. Painting the baseboards later will give you more control and precision, especially in the corners and edges. Using painter’s tape on the wall can prevent paint from getting into the trim, and a brush with a small angle can achieve clean lines. Plus, baseboards require multiple coats, and subsequent coats of paint help prevent the risk of flaking or falling off the freshly painted wall. Another advantage of painting the walls first is the ease of choosing a color and finishing. If you change your mind about a wall color or stop after seeing a sample, you won’t have to paint the baseboards as often. There will be less mess involved in this job because imperfections on the walls are easier to fix than detailed finishes. Good alignment will make you look professional, reduce the need for touch-ups, and create a smooth, unified look throughout the room. For homeowners looking to save time and achieve the best results, following the layout of the walls first, and the floor is the tried and true method. If you want expert guidance, hiring a professional can make a big difference in the quality of the job and finish. For those looking for high-quality, reliable painting solutions, exploring Calgary painting services can help you achieve lasting, long-lasting results for your walls and trim.