Below are different resources available online which the learner may use to study the Polish language on his own.
I have kept the number of resources listed here to a minimum; beyond a few altogether indispensable ones (such as SJP and a dictionary), the most important ingredients to the student’s success are his patient analysis of the Polish before him to infer patterns and his willingness to persevere across not weeks or months but the many years — the Bible in Polish (see below) will sustain him for a lifetime. Anyone under the misconception that Polish may be learnt in three months, as certain ‘modern’ language methods or online personalities may lead one to believe, will be in for a rude awakening indeed.
WSJP and PWN are monolingual Polish dictionaries available for consultation online. As for online bilingual dictionaries, none are satisfying but may include: PONS, Cambridge, WordReference, bab.la, Translatica.
The monolingual WSJP and PWN dictionaries are decent, but one will of course have to understand Polish to use them. I do not find any of the free online bilingual dictionaries particularly useful beyond general vocabulary. I prefer to use the printed Great Polish-English English-Polish Dictionary (Wielki słownik polsko-angielski angielsko-polski) by Jan Stanisławski for my work on this website; I use any of a two-volumed version from the 1960s, a four-volumed version from the 1970s and a four-volumed version from the 1980s. If the reader uses the notes which I have published here to learn Polish, he may consult the vocabulary lists which I have prepared and inserted into the posts.
How to find words in a Polish dictionary: if the learner encountered łokci in his readings and went to look it up in the dictionary, he would not find it: łokci is an inflected form. By using SJP, he will trace inflected forms of words back to their base, dictionary-heading form. By entering łokci into the SJP search field, he will discover that the word in question is łokieć; from there, he may now perform a dictionary search. Any class of word may be entered into the SJP search field.
Polish grammar and pronunciation
Learn the Polish alphabet and how to pronounce the letters on culture.pl or Wikipedia. To consult declensions, try odmiana.net, or Wikisłownik and Wiktionary. A certain number of declensions are available here through the notes on my site; I am always adding new declensions and aim to have presented a decent number of them with time. For verb conjugations, try Cooljugator, bab.la, Verbix.
To learn the grammar of Polish itself, I recommend choosing a text (preferably one for which the learner is able to obtain both a Polish version and a version in his language) and analysing the language of it on one’s own; if the learner were to work his way through the text of the Bible (see below), the grammar of Polish would progressively reveal itself to him and he would not remain perpetually at a beginner’s level, for he would have a great deal of material with which to work across the years.
Reading and listening in Polish
On this very website, the learner may study Polish through the Bible; he may consult the vocabulary and grammar notes as he works his way through the chapters. Using the Biblia Tysiąclecia to learn the Polish language comes with my highest recommendation. Study begins at Rdz 1, which is the first chapter of the book of Genesis. If the learner has chosen to study Polish by this method, he may listen to all that which he has studied: the entire text of the Bible has been recorded.