Tabula Rasa is a very powerful chest armour in Path of Exile, especially when leveling a new character or trying out new builds. This chest will always have 6 linked sockets in which you can use any combination of colored gems, so you can try out new builds very easily with this chest.
Farming for the Tabula Rasa is actually pretty doable compared to most other items, and this is because it can be traded in for 9 X Humility Divination Cards. These cards can drop from The Aqueduct in Act 4 or The Blood Aqueducts in Act 9, so these can even be farmed at low levels, as long as you have unlocked Act 4.
When farming for Tabula Rasa, you want to clear The Blood Aqueduct as fast as possible, and aim to clear the entire instance in about one minute. You want to run in a straight line, and don't go left or right at intersections. This will take you from the entry to the hub area to the waypoint as fast as possible. Kill as many enemies as possible along the way, and pick up all the cards that drop. A good loot filter is needed for this, so you don't have to backtrack to pick up worthless items due to a sound notification.
If you've progressed into maps you could also farm the Channel map. This has a higher drop chance for the cards, but it can be a bit tricky to farm efficiently at the start of a new league.
By clearing it in around a minute, you can expect to get all 9 cards required within 1-3 hours, and 2 hours is a pretty decent benchmark for the chest armour. The item will usually sell for around 20 chaos orbs in Standard League, but can also be vendored for 1 x Divine Orb, which can be worth a lot as well, so this is a fairly profitable farming tactic if you want some currency quickly.
Farming for this item is especially nice at the beginning of leagues when a lot of people want to buy it to use for leveling. This can be a good way to get your hands on some currency the first few days of a league.