Expect to grind grind grind and grind! Although the market now is much better for new players as 6* price has fallen quite a bit.
As to how to earn TE, most ppl already covered the basic. You basically need to sell event items (such as sea shards and soul stones since you are not trying to rank).
Another way is to sell the 4* you get as feeders! lvl40 4* feeders would net you about 5te a set (1 set = 5 units), and lvl 80 4* feeders would net you about 10te a set. I usually sell them at lvl40 since the work it takes from getting them from 1 to 40 is much shorter than 40 to 80. And there is no *quick* way to lvl them normally, but depending on the event, its much easier to lvl them during training events as stages tends to give out LOTS of 2* feeders, and bosses gives out a lot of exp (each Merrow I kill will get a 4* from lvl1 to lvl40, but you have to be able to kill her first...lol)
You also might want to invest in a decent leader card. Common 5* are going pretty cheap, and can help you in recruiting allies and help you achieve the next part. Ignat can be bought for about 5te off the top of my head, but im sure there are better 5* to be had if you do a little bit more research.
Now once you have a decent leader card, you can also try and grind for event 5* (but keep up the grind on those feeders!). They can usually be sold for about 5te each; however, DO NOT sell them during the event, as there will be many flooding the market, and it will be hard to sell one at decent price. Wait until 1 or 2 event after before selling them, since their value will have stabilized by than.
The above way is the slow and sure-fire way to make TE. You can also take the more riskier approach, but faster as well. TE/Pot flipping is one way. There are events where players are willing to trade one pot for 2TE! If you can time it right, you can buy pots and flip them for big profits.
If you are good at bantering, you can try flipping cards as well. This requires a lot of knowledge of the market, and it will take some time before you learn everything. So you can try going to auctions and try to pick up cards at a good deal, than flip them into a better a card/more TE. This also has some risks in it, as people can make bad trades or judgement from time to time.
So, Fanta is a diverse game, and it really depends on your play style to see which way you want to make TE. If one day, you found yourself in a desire to spend, I suggest this to all players, just buy the TE instead of going with the packs, unless the packs has event items that will help you reach your goals. You only hear of the people that do amazing pulls, but in reality, for every success stories, there are 20 sob stories of packs giving them nothing but 4*s.