If you are just coming out of Level 110, you will probably have a number of different Legendary items to choose from. Your Legendaries' special effects will stop working at Level 116, but until then they can be a very powerful addition to help you level up quickly. These are our Legendary recommendations for leveling as an Restoration Shaman in Battle for Azeroth:
Note that the previous method to obtain the tome has been hotfixed and no longer works. Initially, discord user Darethius#8990 has obtained the tome one week ago accidentally by hearthing during the Zul encounter in Uldir on Heroic difficulty. This was unintended and was quickly fixed by the devs. As stated above, to get the tome you now have to kill Zul on Normal, Heroic or Mythic difficulty!
5. at least get 4 characters with these professions. Tailoring/Enchanter; Minning/jewelcrating; Minning/Blacksmithing and Herbalist/alchemist. You can skip blacksmithing and take Minning/herbalist with 1 of your alts. While doing your world quest in argus, try to get all the ores and herbs that you can. Send all the cloth and greens to your tailor character.

The most simple thing is TradeSkillMaster. This AddOn shows you quite an amount of information in the items tooltip. In my opinion, DBRegionMarketAvg the best source. It tells me the price, an item was posted on all EU realms in the last 14 days. Why not DBMarket? DBMarket only shows you the items value from your server in the last 14 days. This value often gets manipulated. Some people start to post an item with a 500g value for 500.000 Gold on the auction house for several weaks. As a consequence, DBMarket is rising towards 500.000 Gold.  If you use DBMarket with 100% and post your item for 500.000 Gold, nobody will buy it.