If you're interested in learning German and don't know where to start, then try cognates.  A cognate is a word that either sounds the same and/or looks the same in two different languages.  So Mutter/mother, Vater/father, Bruder/brother, mein/mine (my), dein/thine (your) - if you learn the pairing (and the sound shift that altered the German from English,) you will quickly pick up new vocabulary.  It's all about rules:  learn the rule, accept that there are always exceptions to rules, and you'll hit a guess rate accuracy of about 80% on new words.

We have learnt already English d went to German t (laut/loud), but also English 'ou' went to 'au', so we can take the example just given and could've guessed the pronunciation of laut as being 'lowt' by those two rules alone.  So what would Maus be?  if 'au' is 'ou' in English, you can guess 'mous', which is correct if you add an e - mouse.  So what are Haus and sauer?  Haus = house, sauer = sour.  If you know Haus is pronounced 'house', you will know how to pronounce Bau, Bauer, sauerkraut, even if you don't know what they mean.

Some more - z or tz are often t in English:  Herz (heart), Katze (cat); ss is often t or tt in English, so besser/better, dass/that, essen/eat, Wasser/water, Beiss/bite, Nuss/nut.

Learn your cognates - they are your friends.  They not only help you guess the meaning of the word, they help with its pronunciation, as there will be a similar English word on which its meaning is based.

Sometimes a similar word can be a false friend - take Gift, for example. In German it means 'poison'.  How could it possibly mean the reverse of the English word, as 'giving' is a selfless, positive activity?  It's because gifts were not always of the nice variety; think of nasty surprises or presents, and the Germans erred on the side of caution linking it to the worst thing to receive, which was something poisonous.  False friend perhaps, but understanding cognates and then the links between the same word in different related languages is part of the fun of always finding something new to learn.  Languages are alive, ever changing, but at the end of the day we are often all linked to a common way of speaking more closely than we sometimes think.