I play for achievements since 8-9 months and I don't do almost anything else in HOI4 now. This is a great fun for me

A few tips from me to have some entertaiment:
1. Don't try take all achievements, if You can't do it! I have 115 now, a few very interesting still left (Prussia of the Balkan + Balkans problem solved, which I try now, Hugeslavia, One king, two crowns, Bevrijding, Go ahead, Macau my day), but I know, that probably not all are within in my reach. Probably I will leave Putting the band back together, because I don't play on non-historical and I don't want to restart my game over and over again, Sun Tzu Reborn, because I don't like world conquest, One Empire from the same reason. I see no point in getting tired
2. At the begging, see some guides on wiki and YT. Wiki has very good and still actuall guides for every achievements. On YT there are a few very good players: Bittersteel, Feedback Gaming, Bubbles Zest, Spaniard, Taureor, Scrumpy Dawg, who show, how to take achievements...
3. ... And try to find You own way

When I took my first achievements, I was trying to do exactly how was explained, but after that most of them I did according to my strategies. For example - Bad Romeance, one of my favourite achievements, on YT has a very good guides, but doing it was to hard for me. I found my own way and I was proud, how I have done it
4. Try to make interesting these achievements, which look not so tempting. Two India's achievements are a good example - You can sit in Asia, waiting to become dominion, research nuclear weapon and wait, until Japan comes to You, but I think, it will be very boring. I always try to play very aggresive, so when I have done it, I defeated Japan, rescured Allies in Africa, Near East and Balkans and I dropped nuclear bomb on Berlin, what ended a war
5. Try to do something different from time to time - not always the same. Treading the Narrow Path - You can do it, simply becoming communist and joining Axis, but when I play Netherlands, I have joining to Axis and helping them to defeat Allies almost every time. So I did something else
6. Try to take as many achievements as You can in one run - thanks that You avoid a situation, when You play almost this same game, or You do something that you could do on the occasion. Good example - Destroyer of the World You can take with the other achievements with nuclear weapon. Or We build it in one day - in every long game.
Have a good fun!