The Sims 4

Well, in addition to what was provided by the other guide (using books), you can also cheat your way into grinding this skill.

So, to do that,you need to do the following :
Step 1 : Press , it should open a command box on the top left corner of your screen, press
Step 2 : Type the following into your command box Traits.equip_trait SteelBladder and then press Start to gain the trait SteelBladder.
Step 3 : Now repeat step 2 but instead of SteelBladder, enter the following traits :
Needs traits : NeverWeary (Energy need never decrease), ForeverFresh (Hygiene need never decrease), ForeverFull(Hunger need never decrease), NeedsNoOne (Social need never decrease). The only need that will keep going down, depending on the skill you're mastering is the "Fun" one.
Useful traits : Savant (Helps learn skills faster), MorningSim (Helps learn skills faster in the morning)/NightOwl (Helps learn skills faster during the night), sadly only one of those two can be picked.
{I believe I have listed all the traits I used to master my skills but if I forgot some, I will add them later.}

Once you are done adding all required traits, you can click on a pond and select "Fishing" and then speed the game on the fastest speed and let your Sim level up its Fishing skill. Thanks to the traits, unless you have a job, you can go from 0 to 10 in one go.
Yes, its cheap, but since it doesn't disable your achievement, why not?

Hope it is useful! Please do leave your comments if you have anything to add.

Pretty self explanatory,

Depending whereabouts you live in the Sims world there are a few Fishing Spots in which you can do this achievement.

All you must do is continuously fish until you reach the maximum level. This is quite a grind but means any fish you catch you can sell for a profit which all helps later in the game.

Hope this helps

Two ways that i know of to get this :

1) Buy the three fishing books, use them to get to lvl 9 fishing. save your game, go waste the day fishing while not worrying about losing job, congrats on lvl 10. i had an 8 member house hold and didnt want to take any risks myself.

2) fish to 10. BORING.

i chose the first one myself.

This video guide ill be linking comes from Billzumanati
If you go to 0:24 of his video and follow along you will download all 9 saves from his tag you will get ALL the achievements from this game. After downloading all 9 worlds you will start a new game, skip tutorial (Select dont ask me again), and open gallery. Hit over to "My library" select "Basket case+", head down to bottom right to place household, replace, select yes, and then hit play. Once loaded select "Willow Creek", from there select "Streamlet Single" confirm and then play. As you've loaded in you WILL unlock the Cast Away achievement and as you're fast-forwarding you will also unlock "Introvert", "The Most Interesting Sim in the World", "All Nighter", "Basketcase", "Games Within Games", and "Beyond Repairs"!







Full video guide:
5:38 Introvert, Beyond Repairs, The Most Interesting Sim in the World, All Nighter, Basketcase, Games Within Games, and Cast Away.

Select New Game (Dismiss Tutorial if this comes up).

Scroll right and select 'Open the Gallery'.

Search for 'Basketcase Family +' and download the family made by 'Misier'.

Select 'Place Household' and choose Replace. After this go to the bottom right and press 'Play'.

Next choose 'Willow Creek' & then 'Streamlet Single'. Press confirm to load up the map.

Finally press the Ultra Speed button and the achievement should pop within a few minutes.

Also unlocks: