This is an incomplete and idiosyncratic list. It merely contains what I found helpful or what I think can be helpful to others.
There are important specialized places for academic philosophical content on the web. To find overview and introductory articles you should consult the Stanford Encyclopedia of Philosophy or Philosophy Compass.
To find articles and books on more specific topics, you should look on PhilPapers.
I’m also very fond of podcasts as a way of getting introduced to something new or hearing other people discuss familiar positions. Here are a few that I like to listen to:
There are many helpful pieces of software that make doing/writing philosophy easier. I am strongly in favour of using non-commercial and open-source products wherever possible.
I do all my writing in non-WYSIWYG editors. That helps me to concentrate on the content instead of getting distracted by formatting. I use a simple editor and the markdown format for short writing (like everything on this website!) and presentations. The great pandoc converter (developed by a philosopher) can make almost any type of document file into basically anything else. I write articles in the .tex format using the editor Kile. Kile then makes good-looking .pdf files, the most practical format for sharing documents.
Anybody who ever has to cite multiple things in a piece of writing should use a reference manager. I manage my literature with Zotero. It exports automatically into .bib files with the BetterBibTeX extension. Those files can be used in .md and .tex files. Extensions for all kinds of office suites are also available.
There are many good resources for academic and philosophical writing on the web already and other teachers have probably given you advice as well. Below I provide some points that I have found particularly helpful advice myself or that touch upon recurring mistakes that I see people make in writing about philosophy and adjacent topics.
Clarity is your friend. You should strive to make your argument as clear and transparent as possible. If that makes your text seem dry and boring to you, that is okay. Academic philosophy does not have to read like a novel. Of course, it is nice to read a clear argument that is also presented in captivating prose, but that is very, very difficult. When in doubt, always err on the side of clarity over fancy prose.
Do lots and lots of sign-posting. Your text should be like a guided tour or a train ride. In the beginning, you should tell your readers the final destination and all the stops you will be making along the way. Along the way, you should remind your readers frequently of where they currently are, where you have just been and where you’re heading next. There should be no surprises in that regard for your readers! Again, this might sound boring, but clarity is to be preferred over style.
If you don’t understand something, you cannot write about it well. If you have problems writing a certain part of your work, consider whether you have actually understood what you are writing about. I find that often when I struggle to write down (a part of) an argument it is because I haven’t actually understood it well. If this concerns my own argument, I have to go back and actually work out the details. If it concerns someone else’s argument I go back to the reading and try to understand it better. But if that doesn’t work, it’s also acceptable to make this problem transparent. Sometimes authors are ambiguous or unclear and then you can say so. Again, clarity is key.