Honestly , I think that you can comprehend it when you practise a lot. At the moment, you should begin with 3 verbs basic for example " amar" "comer" and " beber". You should study all and you compare it with your langague with a scheme .Besides, When you have doubts you should use next link. http://conjugador.reverso.net/conjugacion-espanol.html

How good of a grammar book do you have? If you just learn the rules of Spanish then it's a lot easier than learning every single example. For example, let's focus on gender. I know you Germans use THREE genders but this is a good example. You can "notice" that words that end in "umbre" tend to be feminine in Spanish. Alternatively, you can just remember the rule and apply it to every situation. You really only have to remember like 15 gender rules to get the gender of almost every word correct. La muchedumbre La cumbre Indefinite vs Preterite: Preterite: used for a concrete action. "FIVE days ago I saw Anchorman 2 at the movie theater." (Hace cinco días vi la película Anchorman 2 en el cine) Indefinite: An event that can't be described at one specific point in the past. Or just a description of the past. "When I was young, I liked to go fishing." (Cuando ERA joven me gustaba pescar) Subjunctive vs indicative. Subjunctive: used when you have a change in pronoun and emotion, doubt, possiblity, need. YO necesito que ELLA estudiE español. YO QUIERO que ELLOS me traigan el pastel. The subjuntive is also ALWAYS used with certain sentence constructions. A MENOS QUE sepas cómo hacerlo... CON TAL DE QUE me ayudes con mi tarea... PARA QUE lo tengas claro, te voy a explicar cómo... These "special sentence constructions" have to be memorized, plain and simple. Finally, there are "Adverbial Clauses" that MAY or may not require the subjunctive. CUANDO la veas, dile que la quiero. AUNQUE lo intentes, nunca lo vas a conseguir. Good luck; let me know if I can help you. (PS, we could talk about German, I've always thought about learning it) :)

Maybe what I am goint to write you seems crazy but I think that you should learn spanish the same way a native spanish speaker does. First of all we aren´t worry so much about the right tense or the proper conjugation of a verb. However we speak correctly all the time, because what we have is better. We have a feeling of what is correct and what is incorrect, what sounds good and what sounds strange. I don´t recomend you to memorize a long list of verbs with their conjugations because as time goes by you will forget them and when you are speaking you don´t have the time to think what conjugation is correct for that tense or that subject. How do you adquire that ability that makes a huge difference between a good speaker and a poor one? By input. The best way to understand and speak correctly is by input (of course a right input from native speakers and starting with the most basic phrases). I have used the input based aproach to improve my english and my understanding of this language. You pick a movie or a soap opera, split it in many chunks, the chunk should be very short, with that chunk you replay it many times until you get all the vocabulary and the grammar behind it. do it many times and without noticing it you will adquire the patterns of the language very easily and automatically. It takes time but it is the way we learn spanish: by audio input, repetition, mistakes and feedback. To tell you the truth i don´t know the name of the tenses nor all the grammar that i learned in the school but my spanish is perfect and i don´t have to think about what is correct or incorrect the words just come out of my mouth and I am understood perfectly by others and I can understan what other said.

I feel the same way as you, I am waiting for the answer of your question as well :)