If white solvent-based paint was used on your home’s woodwork (usually the case in the past) it will have discoloured over time - sometimes in only a matter of months. Solvent-based wood paints have other disadvantages too, including smelling, drying slowly (especially when it’s cold), being prone to runs and drops (although non-drip versions are available) and being hard to clean up and clean off things.
Solvent-based wood paints have improved in recent years - a professional decorator recently told me some white ones don’t yellow now - but I still prefer water-based wood paints, as there’s definitely no danger of them discolouring. They also dry quickly and although you have to do several coats of white, especially on bare wood, the paint goes on more easily than solvent-based versions and becomes easier and quicker to apply the more coats you do, so you can finish the job in a day. Other colours usually need just two coats, making them much less work than white.
As well as specific wood/metal paints, you can get water-based multi-surface paints that can be used on walls, ceilings, wood and metal. These are ideal if you want different surfaces to match, as the same colour in a wood/metal paint and an emulsion (for walls) isn’t necessarily identical.
Wood paints were traditionally gloss, but these days lower-sheen satinwood and eggshell are more fashionable finishes. If you’re repainting gloss paint, it’s important to prepare it properly because paint doesn’t adhere well to glossy surfaces. This means you need to sand it to take off the gloss, then apply wood undercoat (or combined wood primer/undercoat) to give a matt finish ready for the new topcoat.
Before painting bare wood, always seal the knots to ensure that the resin in them doesn’t bleed through and ruin the finish. Use knotting solution, which you apply only to the knots, or, better still, paint all the wood with Ronseal KnotBlock Wood Primer & Undercoat (from £7.98 for 250ml, B&Q), which is water-based and nicer to use. This product is a gem because it seals the knots and primes and undercoats in one, saving you time and effort.