Hello all,
Very new to the game. Currently Level 33 Demon Hunter and working my way through the Story Mode. I’m just looking for some tips & advice and anything else that I should know about the game. There’s a lot going on and I want a better understanding of how exactly the game works!
Any advice or tips will be apprecaited!
Thank you!
Welcome aboard!
It is a big topic. As you are new and still doing Story, actually not much tips.
Just kill mobs, hope they’ll drop something good.
I assume that you have bought RoS expansion. If not, I highly recommend.
Useful links:
Grind, grind and grind.
Pick up and sell everything in the early parts of the game. Repairs can get pricey. After you have a comfortable ‘nest egg’ you can concentrate on salvaging items for crafting mats.
Always be aware of legendary items (items with orange background) and their powers (orange text in item description box) and be sure the skills you are using are in sync with them. For example there is a bow that increases your multishot damage but it does you no good if multishot isn’t on your active skill bar. Many new players overlook that part, so keep an eye out.
Use your Templar to help keep you healed. Don’t forget to upgrade his gear as well as your own. His main stat is strength, so keep an eye out for those.
Don’t get discouraged.
Good luck and happy hunting! 
p.s. Above all else - have fun! 
Before you do anything else, go into the Options and enable Elective Mode and Advanced Tool Tips. I don’t know why Blizzard even made these optional, they should be enabled by default.
Next, treat your first go through the campaign as an extended tutorial. Try out the various skills and their runes as they become unlocked so you understand how they work.
Learn how to enchant your items. That is an incredibly useful skill. A lot of people wait until they get good items before they start to enchant them, and often end up ruining the items because they make noob mistakes.
Unless you are really short on gold, it is better to salvage rather than sell items. Those crafting mats will come in handy later on.
Just finish up the story mode as soon as you can to unlock adventure mode.
Thats where the real fun begins.
A QoL change in a patch automatically enables Elective mode when leveling to 38, if I remember correctly.
Not dare to verify if it is still working. But one can always turn it on/off on the options manually.
Awesome, thanks for this. Can you explain more about “Seasons?” How do I start a season?
On the Game Menu click the Switch Hero button. On the Character Selection Menu you can either Create or Rebirth a Character.
During Character creation, you’ll see 2 open boxes. Check Hardcore if you want to play a HC Character. Check Seasonal for a Seasonal Character.
Season 19 has already ended. So, you cannot play Seasons at this time. Season 20 starts a week from this Friday on March 13, 2020 at 5:00 PM PST.
Seasons are special events that take place over roughly a 3 month period. It has various quests and objectives to complete and rewards that can’t be gotten any other way. For instance stash tabs! (1 per season, up to a max of 13)*. Different portrait frames, wings, pets, a complete armor set, a chance to earn mega paragon points. The rewards vary by season. This next season coming up you can receive a pair of butt ugly wings that look like Doctor Octopus arms springing out of your back and a pet that looks like a bat.
Seasons start with Adventure mode opened up, so you can go anywhere in the world you desire at any time - no need to slog through the campaign mode. It also has ‘Bounties’ which give you crafting materials, and special materials to power the all important Kanai’s Cube - an item you can get and use only in adventure mode. It’s a game changer. Let’s you equip additional powers in addition to ones granted from your armor and items. Google it, you’ll get a better idea of what it is and how it works than I can type here. This upcoming seasons theme (each season has a different theme) is centered around how Kanai’s Cube is used. Worry about that when the time comes.
Adventure mode also has Nephalem Rifts and Greater Rifts. These are special instanced maps that give more loot, blood shards, experience, and in Greater Rifts (GR) you receive legendary gems. These are special gems that you can place in ring and amulet slots for additional powers. Again, Google ‘Diablo III legendary gems’.
Next season starts Mar. 13. You’ll like it!
If you want I’ll send you a friends request and when season starts I’ll lend a hand when and where I can?
p.s Forgot to mention, you start season at lvl 1 with nothing. But don’t worry, leveling goes fast. Good players can get to lvl 70 within a few hours (maybe less!).
Others have given you brief description of season. The followings are some offical information:
If you search the internet, there are many seasonal quick starting guide. Many assume you have some experience of the game. They might not suitable for beginners.
If you have any question, please feel free to ask here on New Player Help or on class specific forums. I’d avoid posting on General Discussion because many trolls there. 
Do I need to be a certain level before I start a season?
Nope. Since you start the season journey with a fresh lvl 1 character it doesn’t matter what level your non season characters are.
Also, season and non-season characters can’t interact with each other (except in chat). In season you have your own stash and gold and items, etc. At seasons end all your items and paragon points exp. gets rolled over into your non-seasonal stash. Your character becomes a regular non season then, also.
Next season after that, start the process again.
As Nefertiri stated above:
If you decide to rebirth a Character, you should stash all your gear and your Followers’ gear in your non-Season Stash before you use Rebirth. (Don’t forget your Legendary Potion if you have one equipped).
If you don’t stash your gear when you rebirth your Character, all their gear will be sent to your non-Season mail. Make sure you log in with a non-Season Character to Reclaim to Inventory. If you don’t do this within 30 days, your non-Season mail will be deleted and your gear will be lost.
Good luck and good hunting! 