A tip to get your best whites and it not from DAZ either . Unless you are from the UK you just won't get that opening statement;)
Any way. my method is below.
After all your painting is done then coat the miniature with at least 1 coat ( better with 2) coats of Johnsons Kleer or equivalent. You will probably get the similar effects with a gloss varnish but not tried it with the latter.
This is the key bit. Don't use strong tone dip . Brown IMO is not what we are looking for here . I don't like the Soft Tone either as it makes white a dirt nicotine colour .
Instead use the Dark Tone which is a black pigmented and don't dunk ( bad manners:) ) . Instead place some of the dip into a receptacle. I use old Mouthwash bottle caps for this purpose . Then thin with ordourless white spirit until you get near an ink consistency.
Apply SPARINGLY with a brush onto the model. Leave for around 15 minutes and then clean up with a moistened brush ( white spirit)
Leave for around 24 Hours. Because of the White Spirit dilution it takes longer for the figure to dry.
Then apply a good matt varnish and await to dry.
Reapply if any glossy areas are still showing.
Then gently and carefully reapply white paint to top surfaces like creases in the trousers and repaint all white belts to make them pop.
You should end up with a decent looking model that's whiter than white .
If I had facilities I would show the pictures of my new fledgling Austrian Army. I think its looking quite good and tend to be my own worst ctitic.