I am currently still in the process of trying to learn Japanese, and two of the most important aspects are learning hiragana and katakana.
It is pretty easy to learn all the hiragana and katakana in a couple of days, but it is hard to master them. By mastering them, I mean being able to read them all before they disappear on subtitles. This takes a lot of time and practice, and no matter how good of a memory you have, it takes a lot of pattern recognition to be able to recognize them that fast.
The most helpful resource I have found to help me study the hiragana and katakana is a website called Kana Pro. It seems so simple and plain, but it works better than any other site I have found. On the site, you have the option to practice hiragana, katakana, or both. You can also choose to only study certain ones (such as a,i,u,e,o or sa,shi,su,se,so) if there are certain ones you really need to work on.
The website also has four stages, two where you pick which character matches the English, and two where you see the character and write the English. Overall, it is a super helpful site and one that I use daily. After having used it for the past couple of months, my recognition has gotten much better, and now I am just working on cutting down the amount of time it takes me to finish all 4 stages.
If you are having trouble learning hiragana/katakana, or are just looking for a way to refresh your knowledge, Kana Pro should be your first stop!
Kana Pro Recommendation Rating: 4
1: Something worth checking out if you have time
2: Something that is a hit for some people, but not a must for everyone
3: Something worth prioritizing if interested
4: Something worth making time to check out
5: An absolute home run, worth going out of your way for