So, I first started learning Japanese in school, which meant writing was a necessity, and we started with kana and practised on tracing sheets and later on grid paper (you can get books with grid lines most places you can get notebooks for school, they’re used for math and stuff). These sheets are very similar to what we used in class, but you can find different ones by googling something like ‘kana practice printouts’… The site I linked also has katakana and kanji sheets, but you could also just use this generator and make the ones you need 
Now I recommend learning the principles behind stroke order as you start because otherwise you’ll be memorising it mega inefficiently or else get into awful habits. At first they seem overwhelming, I recommend referring to them as you practise until you get it. The Tofugu guide is popular around here.
To supplement, you could install this userscript, which adds stroke order to the Wanikani display. If you end up using KaniWani (it’s a site that does ‘reverse WaniKani’ in that it shows you English definitions and you type in the Japanese readings to test recall) there’s a setting to enable stroke order numbers, and you could use it to drill writing on a notepad and check your answers (I guess you could also use do this while WKing, but you’re learning material you’re WKing, KW is for recall).
At least on iOS there’s an app called KanjiDraw which lets you drill on your phone. I use an Apple Pencil because I have one, I do not know if I would recommend touch screen practice with just your finger since it is not the same as practising writing, maybe other users can weigh in because I know other users use apps like this.
And of course there are books for this!! Most books that teach you kanji will also teach you how to write them, and so will elementary textbooks. Genki 1 is a very popular starter textbook that has writing practice. There are also dedicated handwriting books, I have no idea about them, sorry, as there are not many scenarios that would make me want to invest that much into writing ><
As to how to improve your handwriting, no clue. shrug This thread is half about stationery but it has stuff on other apps and books too. What's your favorite way to study kanji handwriting? - #33 by DavidOsu
I will add that I would not have bothered to do it immediately otherwise if it weren’t for school, because writing is so painful for me that I do not even do it in my native language. Additionally, I could not think of many situations where I would be writing much Japanese instead of typing it – that may be different for you. And if you plan on taking lots of handwritten notes start writing well as soon as you can, though, and the physical act of writing is extremely good for most people’s memory.