- Estimated achievement difficulty: 8/10 [Achievement Difficulty Rating]
- Offline: 44 
- Online: 9 [although you could argue the seasonal stuff is online as well - I've also included the UGC stuff in this count]
- Approximate amount of time to 1000: 25-50 hours actual play time; this doesn't include waiting a week for a new season [Estimated Time to 100%]
- Minimum number of playthroughs needed: 1
- Missable achievements: None
- Does difficulty affect achievements: Only Unbeatable Triumph (30G)
- Unobtainable/glitched achievements: None
Forza Horizon 5 is the latest masterpiece in open-world racing from Playground Games. While the completion is significantly shorter than other games in the franchise, there are some achievements that are quite difficult, and are largely based on who you get matched up again in online games.
There is no right or wrong way to approach the Forza Horizon 5 achievement list, so all I can do is offer advice: complete all the main events first (all the events on the Horizon Adventure map), as this will not only give you cars and Wheelspins along the way to help with some of the other achievements, but it'll also give you a ton of cash and you'll fly through the levels too - again, helping you with the other achievements. By the time you've done all the races in the main adventure you'll pretty much be in the Hall of Fame, and then it's just a matter of mopping up the photo achievements and the PR events. And then of course you can turn your attention to the online achievements and beating the Unbeatable Drivatars. Gulp! Good luck!
Most of Forza is just mopping up, to be honest, due to the open-world nature of the game. Definitely focus on the more offline achievements first (although you can play the whole game in co-op, so that kind of makes the whole game online) before heading online. For one, it's good practice, and two, it'll give you a nice garage of cars to compete with on multiple levels.
Forza Horizon 5, when it comes to recent Forza games, is probably the hardest (achievement-wise) for quite a few years, but it's so much fun and is bloody brilliant, so play it, enjoy it, soak up Mexico, and get some achievements along the way. Sure, winning an Eliminator and beating the Unbeatable Drivatars is a bit of a pain (without our cool, cool tips!), as can be winning races online, but whatever happens, you'll have so much fun along the way anyway, and that's what matters!