D&D Beyond is the best way to have a digital version of your character. I have campaigns set up there for each of my classes. Any of my players that use D&D Beyond should contact me to coordinate it so that their character shows up in the campaign for their class.
RPG Card Maker is what I use to make the spell cards for my players who use paper versions of their characters. It is an easy to use editor that lets you make almost any type of card in all kinds of sizes.
HeroForge is the premiere figurine creator. They have tons of choices and for only about $9 you can get an STL file of your character that you can 3D print. For about $20 they will print it and mail it to you.
5e Magic Shop Generator is great if you need to quickly come up with a place for your adventurers to shop.
Token Stamp is the easiest way to create a virtual or printable token for characters and monsters. You drop in an image and it makes a picture with a border. Simple, quick, easy.
The Monsters Know is a blog with detailed entries showing how to play the monsters so that they aren't just simple bags of hitpoints. Search for the monster your party will be fighting and you're likely to fins an article that will improve the battle.
I have a standard list of paints and techniques I use for terrain crafting listed here.