Wee dictionaries are a good way to build your basic vocabulary.
This is by far the most popular guide to the language of today's Scotland, with nearly 1800 everyday words and phrases from the Borders, Lowlands, Highlands and Islands clearly explained and with lots of helpful examples of usage.
The next step is the Essential Scots Dictionary, designed for learners.
Originally produced by the Scottish National Dictionary Association and first published as the Scots School Dictionary from 1996-2003, this dictionary is ideal for use by students of all ages. It is also a useful compact reference book for anyone seeking information on modern Scots.
There is a free app version of this dictionary, too.
From the same stable, but a little more comprehensive and useful for writing is the Concise English-Scots Dictionary.
What do you call a paper bag in Scots? How would you describe a dull day in Scots? First published in 1993, this comprehensive dictionary of words and phrases is for anyone who wants to use the Scots language.
Once you are about this level, the Online Scots Dictionary is very useful and popular with writers, from Scots to English or English to Scots. An Android Scots Dictionary App is also available via Google Play.
For more advanced scholars the Scots to English Concise Scots Dictionary (now in its Second edition) is a treasure trove.
The Scots Thesaurus should also be on any writer’s shelf.
The Concise Scots Dictionary (2nd edition) is the ideal reference work for readers, learners, speakers and students of the Scots language. Updated in 2017 from the first edition in 1985, it is the single most authoritative volume on the history, pronunciation and geographical distribution of Scots words.
The Scots Thesaurus was first published in 1990 and is a unique subject guide to over 20,000 Scots words.
Finally the DSL Online contains the motherload of ancient and modern Scots vocabulary, but if you are a new writer needs to be treated with some caution!
DSL Online brings together the two major historical dictionaries of the Scots language: Modern Scots (after 1700) in The Scottish National Dictionary (SND) Older Scots (before 1700) in A Dictionary of the Older Scottish Tongue (DOST)