Hello!
Want to have some HoI4 achievements easily without making much efforts?
You chose the best guide!
I selectioned what i think are the 20 easiest achievements that you can get even without having DLCs, so let's get started!

note: the difficulty depends on how actually good you are at the game, but if you are a bit good, you should be able to get all the achievements i listed.

also, this is my first guide, i will look forward to update this when i can, be sure to rate the guide, so that I understand whether i should do more improvements

- Join a faction -
I think there's nothing difficult about this one, just play as france and join allies, or play italy and join axis, I personally suggest doing this achievement playing as portugal since if you join allies, you manage to get the "BFFs" achievement

- As Portugal, join the same faction as Great Britain -

As said before, play as portugal, go down the democratic path, and as soon as you can join the allies

- Reach 1948 -

This is a really boring achievement, just pick a neutral nation which doesn't get any war goals on, put the game at 5 speed and wait until 1948, if you want to do this achievement while actually playing, pick France and try to resist the German invasion, if you survive until 1948 you will also get the "Vive la France" achievement

- Reach 1948 as France without capitulating or surrendering -

Resisting as France until 1948 is not an easy challenge, but i suggest building level 10 forts along the borders of Belgium, Luxembourg and Italy, while also forming a good army, in order to gold the german invasion and hopefully, counter invade them.
Doing this achievement also gives you the "Time is on our side" Achievement

- Reach 0 manpower with Scraping the Barrel as Conscription Law -

This Achievement looks difficult, but you just have to pick Tannu Tuva, reserve some political power, and when the USSR goes to war, switch to Scraping the Barrel and deploy as many divisions as possible

- Join Axis as Canada -

In this achievement, you just need to go down the fascist path, become fascist and join the Axis, nothing too difficult and it doesn't take much time

- Have at least 1000 convoys -

for this one, i suggest playing USA, because it's the nation which has more dockyards in the start and more civilian factories that can be used to build more dockyards to speed up the process, what you want to do is delete every single ship that is being built in the production line and replace them with convoys, assign as many dockyards as you can, once reached 1000 convoys you will get the achievement

- Research Construction V -

This one will take a bit of time, but just get a random nation and reserve a research slot for the construction part, keep researching construction until you reach contruction V

- Lead a faction with at least 20 members -

I suggest doing this achievement as germany, what you want to do is win ww2 and satellite as many states as you can, they will automatically join the faction, doing this will also permit you to get the "The Puppetmaster" achievement

- Have at least 51 subjects -

As said in the previous achievement, as germany winn ww2 and satellite as many states as you can, but if you have the "La resistance" dlc, you can pick uk and release every state as puppet.

- As Germany have both Poland and France surrender before January 1st 1940 -

I suggest that, as germany, once the game starts you justify against poland and annex it as fast as you can, than, you immediately prepare and declare war against france and make it capitulate before January 1st 1940

- As South Africa, have 9 civilian factories in Transvaal -

This just takes time, start building miltary factories in Transvaal and convert the civilian factories to military factories, also, go down the concentrated industry path in the industry research section, so you will be able to build more military factories

- Deploy a Nuke -

For this achievement, just pick USA, focus on on building planes, especially strategic bomber and research all the nukes researches, it will take long, but eventually, you will be able to nuke, declare war on a small country and put all the planes you have over it, click on a random province and click the nuke button

- As the U.S.A., drop a nuclear bomb on Paris -

This one looks difficult, but it's actually easy, just wait for germany to invade and capture france, join the allies and put your planes over france, once you have enough air superiority (>75%) nuke Paris

- As the U.S.A., have more than 300 military factories -

I suggest just get rid of all the debuffs usa starts with and start buiding military factories, the only "problem" is waiting

- Research all rocket, nuclear and jet technologies -

Just pick a neutral nation and start researching, if you're good enough do it with poland, you should be able to get the "Poland can into space" just researching the rocket tecnologies

- Win Spanish Civil War as Republican Spain -

If you're good at playing, this should be very easy, learn the weakness of the fascists and in the war against them

- As Nationalist Spain in Axis manage to take Paris before the Germans -

It does look difficult, but it's actually easy, you don't actually need to reach paris before them, just wait for someone to conquer it and then ask to get the region

- As Britain, declare war on one of your former subjects -

Become fascist, the puppets will leave the faction, then declare war to Canada, since it's the one which has less divisions

- As Greece, liberate Albania while being at war with Italy -

focus all your divisions in the border with albania, they usually attack with low quantity of divisions, so push forward and capture all of albania