Before you paint iron surface, if it has not been painted previously, it needs to be degreased with a solvent. To do this, wet a rag in solvent and carefully wipe the surface. Then apply a primer for iron and allow it to dry. Then you can apply the paint. Should not be painted with a thick layer, as can be formed smudges. A second coat of paint, apply after drying of the first.
Painted surfaces that were previously painted, you need on the same principle. But ensure that you do not need. Just apply several layers of paint. If possible, you can pre-apply primer.

If the old layer of paint is thick enough, then sand it with a sander. Then Prime and apply the paint.

The average time of drying of the layers ranges from 5 to 24 hours. It all depends on the type of paint.
Wood surfaces need no further processing. If the wood is not painted, it will be necessary to apply paint in three coats as the first coat will be absorbed into the tree structure.

If the old paint started to otsenivaetsya and formed bumps – scrub the surface. This can be done with a spatula or a special grinding machine. Then sweep up the chipped off paint and start staining.
Latex paint applied with a roller, and in remote places and on small areas – with a brush. The surface is pre-primed. After a few hours you can start painting.

Latex paint can be applied in a single layer, if it is laid down tightly and smoothly. If not, then apply a second coat of paint.