as a German myself I recommend that in spoken form, do not worry about grammar (i.e trying to do all the cases correctly). It is not necessary to understand you. For one, you can't actually do the cases properly until you know all the article for the words any ways... and if you can't remember if it's der, die, or das, just use der... any ways any german will know what you mean even if you do not use the right article. do not worry so much about that. do not worry about doing dative case and such perfectly (or even at all) in spoken form, this will literally take you YEARS to get the hang of, and again, not that critical.
what you should focus on:
Pronunciation. This is very important, in German we pronounce *every* letter in a word, there are some rare exceptions, but vast, vast majority it is all pronounced. Think of "knoblauch", that means garlic, do not say it like in English with a silent "kn", say the "k", like "keh". That means also learn your ä, ö, ü. These are their own parts of the alphabet, they are not equivalent to a, o, u. If a word has ä, ö, ü, and you do not pronounce them but rather like a, o, u, people will struggle to understand you, and you will be guaranteed have to repeat yourself.
Also in spoken form, in Germany, we rarely, rarely, ever use FUTURE TENSE. In English future tense is so common. Not in German. e.g. We do not say "I ***will***" etc, trying to use future tense in Germany is unnecessarily complicated for a beginner and colloquially it is not common.
I think this is most important. Once you know this, and learn your vocab, you can communicate much better.
Pronouns/verbs/conjugations.
e.g for kommen (come);
Ich -e (I): komme/heiße
du -st (you, informal): kommst/heißst
er/sie/es -t (he/she/it): kommt/heißt
wir -en (we): kommen/heißen
ihr -t (you all): kommt/heißt
Sie/sie (former formal, latter plural) -en: kommen/heißen
Your W-Frage (literally w-questions):
wo: where
wer: who
wie: how
was: what
warum/wieso: why
wann: when
wie
etc
Commonly used verbs:
Sein (to be) / Haben (to have)
ich: Bin (am) / habe
du: bist (are) / hast
er/sie/es: ist (is) /hat
wir: sind (are/they) / haben
ihr: seid (are) / habt
Sie/sie: sind (are/they) / haben
Separable Prefix Verbs
Auf, aus, an, ein, ab, mit, nach, vor, …
when you see these with verbs, then you can make sentences:
e.g Anfangen - Der Deutschkurs fängt um acht Uhr an.
Possessiv pronouns:
you add the -e when it is feminine/plural. this means you must know the article of the word, but again don't worry about it if you you use -e when it's actually masculine, so dein/deine for e.g if you get them wrong, it doesn't matter that much.
e.g dein Hund (your dog - dog is masc, der Hund)
deine Katze (your cat - cat is fem, die Kat)
ich: mein/e
du:dein/e
er: sein/e
sie: ihr/e
es: sein/e
wir: unser/e
ihr: euer/eure
Sie (formal): Ihr/e
sie (plural):ihr/e
Present tense (haben - "to have") / Past tense (hatten - "had")
ich: habe / hatte
du: hast / hattest
er/sie/es: hat / hatte
wir: haben / hatten
ihr: habt / hattet
Sie/sie: haben / hatten
Present tense (sein - "to be") / Past tense (waren - "was")
ich: bin / war
du: bist / warst
er/sie/es: ist / war
wir: sind / waren
ihr: seid / wart
Sie/sie: sind /waren
Learn how to compound sentences, this is actually easy and you can do it like you do in English, like "weil" for because, "jedoch" for however, "und" for and, "wenn" for if, etc.
I did not mention dative/accusative case etc here, because you will be surprised, if you learn above, how to compound sentences, and some vocab, how far you can go with conversing in German while trying also construct your sentences sort of like in English.