Man kann mehr zu lernen versuchen. Man muß es sich nicht so vorstellen, daß man etwa von der Vorsehung plötzlich die großartigen Deutschkenntnisse erhalten kann. Die eignet man sich nur durch mühselige Arbeitsamkeit an.

Practice!

Pick a concrete example that you don't understand, and ask here. It's easier to explain with help of an example. For the declension, there are tables. There's almost no surprise here, just look up the gender of the word, and then the endings can be found in the appropriate table. In general, as in English, it's the verb the governs the sentence structure. As in English, every verb can be used with several "patterns" that dictate which cases/propositions to use. A good dictionary will tell you those patterns. (The Oxford English Dictionary does this for English verbs). The main rule for word order is that in a main clause, the conjugated verb is in second position, and in a subclause, the conjugated verb is in last position. Everything else is flexible (to a degree). Not sure if this already helps, but maybe it's a start.