Rule no.1 - When performing a mindless task, ask yourself the following question: Are there gaps in which I can slot painting into? If there are, DOOO ITTTTT! Even computer games can offer potential for this (loading times, etc).
Rule no.2 - Eye contact is overrated. Conversations with other people can be accomplished while painting. Warning: This is not well understood or appreciated by WAGS. ATTEMPT IT AT YOUR OWN PERIL.
Rule no.3 - Painting in itself is divided into two main types: The type you really have to pay attention (highlighting, free hand, fine details) to and the type which requires only time, such as base coating and the first layer of highlights. Try to have some parts of your army which require the latter on your desk, so that if you fancy some stress free monotony or find yourself in the middle of a long phonecall, you can multi-task. The second type of painting can often prove a bit tedious. Remember to have a comedy or the radio playing in the background, if you can't find someone else to paint alongside with.
Rule no.4 Make sure that when painting a miniature you start off with the areas that are forgiving in terms of slopiness. Areas which are drybrushed are extremely good candidates. You can do them quickly and in the process you'll only be splashing paint onto areas you would be painting over anyway. Metallics are a good example where this approach works wonders.
Other general hints and tips.
Leave all white and close to white colours till last. They easy get dirty in the process of painting other colours.
Make damn sure that your layers of highlights are actually visible.
With layered highlights, I'm starting to think that although it might seem counter initutive, it can be better to work backwards, with the sharpest highlight first. This is because you quite often have little area to work with. The other way means that you quite often end up not covering enough the area with the first or second stage of highlights. My approach works best if you already know the colours you will use and therefore lends itself best to armies.
Another issue with layered highlights is that sometimes you don't paint the first layers thickly enoughly (by this I mean how far the highlight extends into the main surface from the edge you're highlighting). In general it is better to start with what initially looks like too large of a surface, as you can always go back with the base colour and neaten it up later, but if you've not given yourself enough room, it's far more difficult to rectify.