I prefer the Liberon acrylic water based dyes. There is a good range of colours and you can mix them or dilute them with water. experiment until you get the right shade but you will need to put your varnish, sanding sealer or polish on top of the test area to get the full effect. water varnishes penetrate fiarly well into the wood and are quite good at resisting fading compared with some others.
For a quick job when there hasnt been time to muck about experimenting with colours and waiting for water stains to dry, I have also used a coloured shellac polish - there are proprietry ones made up out there, but I mix some spirit stain powder into garnet shellac and apply with a rubber, or maybe a brush for small areas / mouldings / carvings. Cant go too heavy with the colour though or you get a horrible load of streaks of colour. Bonus is that if you get it all wrong it comes off with a quick wipe of meths and you can start again straightaway. It is also fully reversible for future restorers which is always good practise. A few coats and if its already dark enough but still not polished enough, switch to transparent polish to build it up, then wire wool down and wax with a coloured wax which you can choose the colour of to further enhance the finished colour.
Pat