self-teaching german would be hard i think because german is a difficult language.
if you really want to do it, i would begin with simple sentences to get used to the vocab.
learn the pronouns, the most important verbs, some nouns and adjectives
e.g.
"Ich trinke Kaffee" - "I drink coffee"
"Er hat ein Auto" - "He has a car"
then take a look on how to link two sentences. ist german there are "Hauptsatz" and "Nebensatz"
in english the syntax of the "Nebensatz" is equivalent to the "Hauptsatz" but in german you need to put the predicate in the "Nebensatz" at the end.
e.g.
subject, predicate, object [because] subject predicate, object
"I drink tea because i am thirsty"
in german:
Subjekt, Prädikat, Objekt [, weil] Subjekt, Objekt, Prädikat
"Ich trinke Tee, weil ich durstig bin"
practise writing some texts like letters or dialogues as often as possible to get used to the sytax and the vocab.
after that learn the basics of the nominative, genitive, dative and accusative.
you need to know this to choose the right suffixes of the adjectives.
e.g.
Nominativ: Der schöner Mann (Wer oder was/who or what)
Genitiv: Des schönen Mannes (Wessen/whose)
Dativ: Dem schönen Mann (Wem/whom)
Akkusativ: Den schönen Mann (Wen oder was/who or what)
always pay attention to pronounce words correctly. you may find some good dictionaries with the phonetic transcription of every word.