A common mistake of new players is to upgrade their gear at every opportunity, paying for a new piece even if it will only add one or two new stat points over an existing item. Likewise, investing in headgear, neckwear, trinkets, and rings at the earliest available levels can also consume valuable cash. While it might seem foolish to leave an available slot empty, you will eventually find something to fill it. Blizzard will see to it via the quest rewards you'll get along the way. In the mean time, the 1 or more you save will serve you well if you invest it wisely. The bottom line is that one can easily level all the way to the maximum relying on just quest/drop greens. The gear you get from regular questing can help you perform well in dungeons, which gets you even better equipment.
Healing effect looks kinda cool but is very minor, and barely worth using. The guardians again look cool, but are unsurprisingly pretty terrible in combat as well (at least from what I hear, I haven't quite got this one myself yet). And since the blood contracts aren't sellable I don't think, the profitability of this is nil (and even if they were... meh), as you lose cash from the crafting cost. I would probably recommend not crafting this one.
Swim Speed Potions (used especially at lvl 37 for Faldir's Cove in Arathi Highlands and lvl 57 in WPL). Try to get multiple stacks of these. I also recommend keeping a stack of these always in your bags. You will frequently pass rivers and lakes and can use these potions to pass them faster through out the guide. Please note that these potions do not stack with Druid's Aquatic Form and Glyph of Aquatic Form.
When assigning a selling price, do not aim for too low a price that would give you too little profit, but certainly do not assign too high a price. Too much greed is never a good thing, and the AH is filled with items that do not sell due to excessive inflation. A very common tactic in the AH is to sell for lower than what another player is offering, and many players make a lot of money that way. Similarly, losing sales thanks to being undercut is never fun. Aim for as low a price you can that will still make you a good profit. If you can keep producing the same item over and over, sell cheaply yet make a good amount of the item, you will reliably make a lot of money by volume. Moving inventory is the best kind of inventory.