A useful dodge I've been using a lot today during running trials is the little-bag-full-of-liquid-lead trick. When trying to work out how much extra weight to add to a loco a selection of these (the one shown weighs 100g) is useful. It's a lot easier if you can plonk weights onto the vehicle concerned when it's struggling up the grade on the layout and see how much is needed for it to find it's feet. Putting the weight into bags means they mould themselves to the roof and don't slide off, but if they don't stay put you can always add a piece of masking tape.
The little bag being used actually contained a set of Express Models DCC lights for a HST power car before being pressed into service for the weighting game.
Dodge number 2 is a set of temporary connectors I use all of the time for trying out different decoders in locos. Whilst a proper NMRA DCC socket as seen on the likes of the Heljan Class 47 makes this kind of experimentation child's play, most UK outline stock doesn't come with anything quite that sophisticated - we're barely out of the clockwork age.
To make my life a little bit easier I use 4 short pieces of wire soldered to a couple of two pin sections of socket strip, product code DC17T from Maplin. These are then temporarily soldered to the selected loco - nothing fancy as you only need to connect the red, orange, black and grey wires. The photo shows a Zimo decoder plugged into these sockets and being identified as the best performer in a Hornby Class 86.