DnD is a game that is constantly evolving. It relies upon the group to work well as a team so that encounters, roleplay and group dynamic is all fun for everyone. Much of the onus for a great game lies with the DM, but the DM is only as good as the group. Here are some resources that you as a player can utilize to ensure you're making the most of your time at the DnD table.
1. DnD Beyond
As a pen and paper elitist it pains me to recommend DnD Beyond, but the reality is from beginners to veterans DnD Beyond is a great tool. It's an incredibly efficient way to build a character, and it makes rolling and running your character fast and easy. One of the most useful parts is how fast it is to look up spells and magic items, while keeping everything consolidated in one easy to read place.
Again, as a dice retailer this is painful, but the Wizards of the Coast dice roller is super useful and easy to use. It works great both on desktop and mobile, is easy to read and makes it easy to increase or decrease the number of each dice you want to roll.
A simple tool, but one that is great for inspiration. All this website does is give you a class, race and very basic set of backstory and personality points. You can click through and randomize as many times as you want, which is great for getting ideas before getting down to character creation.
4. Hero Forge
A service that lets you design and purchase your own custom miniature. Not only can you build the perfect mini, but the website lets you screenshot your custom character mini for free, so you can easily create an image of what you want your character to look like totally free of charge. They have tons of assets to choose from, all the DnD races and tons of customizability.
Here you can find a wonderfully useful list of websites that consolidate the rules that apply to a given situation. There are some that are simple and some that are dense enough to explain everything like conditions, spellcasting requirements, combat actions and adventuring rules. They are great for keeping a handle on what you can and cannot do in any given turn. This isn't meant as a suggestion to be a Rules Lawyer, but knowing your options makes decisions way quicker when the DM gets around to your turn. It's also helpful to know your options when you want to make a check of some kind.
Like learning any skill or getting into any hobby, there are tons of well-informed and passionate people on youtube. In fact, most social media platforms will have groups of people working to inform and help with how to build characters, how to roleplay well, and any number of important parts of DnD. The link takes you to Bob World Builder, who is one such passionate and well informed creator, but there are tons of great DnD youtubers that do more than just play the game.
Hopefully this little list will lead you to something useful. There are tons of resources out there, and if you have questions or are looking for ways to become a better player there are many resources that can point you in the right direction. And, every player needs dice.