My best tips for making gold:
1. Never farm anything, the gold needed to start trading comes from levling to 70.
2. Buy low, sell high (take note of prices over a few weeks to get the "feel" for them).
3. Spike prices when the supply on the market is low.
4. Convert items and sell for a profit with the help of friends. Offer them free services of your profession(s) in trade.
5. Never deal and/or try to make a profit with items that are commonly used, eg: Terocones, Nightmare Vines.
6. Do not stare blindly at max level items, low level items can go way higher.
7. Think long-term, not short term. Hence you stack up on items you believe people will need in the future.
My best tips for saving gold:
1. Cut your spending (duh, how?) by stop using items like Haste Potions that barely has an effect on your overall DPS.
2. Raid with professions that can ease the burden, an example would be alchemy for Alchemist's Potions.