Can you take the test in your own language?
Here's something a lot of people don't find out until late: if you're older and have held your green card for a long time, you may not have to take the test in English at all — and in one case, you only have to study 20 questions instead of 128. The rules come down to two numbers: your age, and how many years you've been a permanent resident.
50/20 and 55/15 — test in your language
If you're 50 or older and have had your green card for at least 20 years, or 55 or older with at least 15 years, you're exempt from the English part of the test. You can do the whole interview — civics questions included — in the language you're most comfortable in, and you bring your own interpreter.
The catch people miss: you still take the full civics test. All 128 (or 100) questions are fair game — just in your language. So this helps with English, not with how much you have to study. An easy way to remember it: 50/20, 55/15 — the older you are, the fewer years you need.
65/20 — the one worth checking for
If you're 65 or older and have had your green card for at least 20 years, you get the best deal of all. You're exempt from English, and you only study a special list of 20 questions instead of the whole pool. The officer asks 10 of those 20, and you need 6 right.
On this site you can turn on "65/20" in the settings and it filters straight to those 20 questions, in your language. If you qualify, this changes how you study more than anything else — there's simply far less to memorize.
Counting your years (and a common mix-up)
"Years as a permanent resident" means years since the date on your green card — not years living in the U.S., and not years since you applied. And these are age-and-years rules: you need both halves. Being 60 doesn't help if you've only had your green card for eight years; you'd still test in English.
Count carefully, because qualifying changes which questions you even need to open.
A different path: medical disability (N-648)
There's also a separate exemption that has nothing to do with age. An applicant who can't learn the material because of a physical or developmental disability or a mental impairment can have a doctor complete Form N-648, which may waive the English requirement, the civics requirement, or both. If that might apply to you, ask your doctor or an immigration lawyer about it.
None of these apply automatically — you confirm them at the interview, and USCIS goes by the date on your green card. But if you qualify for 65/20, study the 20 starred questions in your own language and you'll walk in with far less to memorize.