I feel bad for anyone learning this language.
clearly you have never tried out German :-)
As a German native speaker who generally has a lot of difficulty learning languages, I can assure you that English was a lot more feasible for me compared to anything else I tried.
(Of course you'll find an error in this comment - that is bound to happen in any comment talking about language mistakes)
The rules of English are relatively simple but there are a ton of exceptions that take a long time to get right and will give it away you're not a native speaker.
German doesn't have as many exceptions so you can easily reach near-native levels of fluency once you know all the rules, but there are far more rules you need to be aware of (and even then you'll need to keep track of grammatical gender).
In other words, you can learn German by simply following all the rules and memorizing the vocabulary, but it's far easier to do for English (where you'll miss a ton of exceptions if you only do that).
Let's just say I'm happy I'm a native German speaker already -- I probably couldn't be bothered to become as fluent in it as I'm in English as a second language.
Dutch, on the other hand... :)
I've been trying for five or six months now to pronounce 'Groningen' right, but I never succeeded. If there's one 'g' in a word, I can pronounce it. If there are two letters 'g' in one word, it's practically impossible for me.
https://en.wikipedia.org/wiki/Determiner (If you want to hate English slightly more :-) )
Drop in the bucket, but my small part towards decreasing the number of exceptions.
Edit: and just personally, I try to mentally associate homophones (two/too/to) with another word that helps clarify them (e.g. too:also).
Obligatory QI citation: https://www.youtube.com/watch?v=duqlZXiIZqA
And for plural "s": if the word normally ends in a "s" or "sh" or "z" sound (or possibly even "zh", i.e. the "j" in French "je") add an "es" instead of "s". Some words are irregular but irregular words by definition don't follow the rules.
The real confusion comes with possessive pronouns. It is "the boy's pet" but it is "his pet" (not #"he's pet"). They're not nouns (they're pro-nouns, i.e. something that is used instead of a noun) so the apostrophe-s rule doesn't apply to them, they just take on special forms.
The confusion really just stems from English regularly allowing contractions like "-'s"/"-'" for "is" and "-n't"/"-'t" for "not" or "-'d" for "would". Pronouns can have contractions as suffixes (e.g. "he's" for "he is" or "he'd" for "he would") but nouns normally can't (#"the boy'd" isn't normally permissible, at least not in writing).
It gets even worse if you consider that whether words can only be contracted additionally depends on their pronunciation (and role) within the sentence. You can't answer the question "Is he dead?" with #"He's.", for example.
Oh, and I haven't even touched upon similar-sounding but entirely different things like "their" vs "they're" -- and I even caught myself accidentally mixing them up while writing this comment.
