So here is what I do when I need to find upgrades for my characters: go to Ask Mr. Robot
--> You need to load your character, so pick US - Wyrmrest Accord - Songlark (for example)
--> You will see a screen that shows the gear you logged out most recently in (so if you really want to get the most out of this site, log out in the gear you want to optimize).
--> Click on the green arrow that is to the right of your characters name. You will see a list of options. I most frequently use optimize gems and enchants and BiS.
--> You can optimize what you are currently wearing, to make sure you have the right enchants/gems. Additionally, you can login to the site to see if you have any gear in your bags which may be more optimal.
To Find Upgrades: --> Click on the green arrow again, and select Best in Slot.
--> A little below your characters name, you will see a blue arrow. Click that. Now, you can change what gear is inspected for BiS...i.e. we aren't currently raiding mythic BRF so you don't need to look at gear from that instance! To the right of the header "Best in Slot" you can click "Drop Locations" for a nice handy list of where all your BiS gear drops!
--> I usually have it set on Blackrock Foundry Normal, and High Maul heroic. If you are playing a new character, you can focus on LFR and crafted gear. If you are rolling in money you can include BoE gear.