When it comes to rolling out the walls never ever use a cheap foam roller. Foam rollers never evenly absorb the paint out of the pan and will actually add time to you project and cause more mess. Buy yourself a synthetic professional 3/8 nap roller head for about $6 to $8. Not only will the paint be applied in a smoother fashion you will experience less work and mess.
One precaution: You can't paint with it in cold weather. The chemical reaction that transforms the water solution into a durable finish will not take place if the temperature is below 50°. (Conventional oil paints don't stick well in cold weather, either.)
If you are grappling with the problem of choosing a woodwork colour to go with neutral walls, check out Architectural Colours by David Oliver, the founder of Paint & Paper Library. He arranged his off-whites for ceilings, cornices, walls and woodwork in chromatical groups and the concept has been so well received that chromatically arranged colours, such as soft greys, greens and pinks, have been introduced.
Remove side view mirrors (unless they're to be body color) as well as exterior door handles and locks. This will take some extra time because you need to remove the interior door panels to get these off, but it's worth it. Head lights, tail lights, marker lights and license plates should come off too, but you'll need them in place to drive to the paint shop. So bring some tools so you can quickly take these off once you arrive. Depending on the year Mustang you can just take off the chrome bezels or rings. The shop can then easily mask the headlight or tail light itself and still get plenty of paint around the edges.
Alkyd has solid advantages overriding the slight cleanup in-convenience. It is exceptionally tough and very resistant to scrubbing. It stands up well in the trouble spots - trim, bathroom, kitchen. And it is easy to apply, producing a smooth, even finish free of streaks and brush marks.
Alkyd is an old interior paint made newly popular by a change in solvent - a super-refined petroleum chemical that has almost no odor. It is not a water paint. You thin it and clean brushes with mineral spirits or turpentine, or, if you want to retain the odorless feature, with the new odorless solvent. (Ask the paint-store man for just that, odorless solvent).
Can you feel the rhythm in repeating some color or combination?