Textured paint hides cracks, but not well. The truth is that texture will hide only about 10% of the blemishes. I have found that a surface needs to be very smooth before texturing it. Cracks, bumps, and curved plaster will show through a thin texture finish. So, if you texture to hide cracks, don’t expect too much and you won’t be disappointed.
If you are forced to fix the existing ceiling, use joint tape and joint compound to first bind all the cracks together. This will help prevent cracks from reappearing at the next change of seasons. Use thin coats of joint compound. Don’t try to do two coats at a time. You’re no Michelangelo and you will only waste time, while doing a bad job. Too thick a coat of joint compound requires a long time to dry. Plus it usually requires sanding, where thin coats dry faster and you can skip the sanding step.
After two coats of compound on the tape have dried, carefully feather from the center of the tape to a distance of about 12 inches out onto the ceiling. Use a wide trowel to apply the compound. Now it will be much more difficult to see the joint. You will need three coats for a good job. Three coats of joint compound around the room and you may not need to texture.
A better repair is to drywall the ceiling. Now all the drywall joints are flat and are much easier to ‘mud-in’. Plus this method eliminates any chance of cracking in the future. Believe it or not, sometimes this can be done in less time than fooling around with all your cracks.
In either case, a final sanding is usually required. Apply two coats of primer before you paint.