How to remember different variations of openings

So, I want to use what I learned studying the Najdorf Sicilian, but whenever I play it, I can only remember one variation, other than like at least two or three. Any tips to Improve memorizing lines?

Do not memorize lines.
Study games.

.

I hear and I forget.

I see and I remember.

I do and I understand.

- Confucius

well i dont have one

As this was downvoted, I'll delete it. Sorry to offend anyone. Good luck.

what a handsome father figure. I hope he doesn't commit any vile actions like genocide in the future

Tygxc is correct... studying games is far better than trying to memorize sequences of moves.

Here's how I do it. Your mileage may vary.

I compare my chess "memory" to a closet. Memorizing lines of play is like packing stuff away in the closet. You can't just stuff things in haphazardly... you'll never be able to FIND anything afterwards.

The best way that I've found to do it is to outfit your closet with multiple shelves for laying stuff out in an organized fashion, and with rows of hooks for hanging individual items from.

Translating that rather obscure analogy into plain English, I find that if I understand the important plans and key squares associated with the line, as well as the opponent's typical counters to them, then it becomes FAR easier to memorize the sequence of moves.

... and I learn the plans, key squares, typical tactics, endgames etc by studying games, not lines.

that's brilliant

That's why they pay me the BIG bucks.

... actually... wait... they don't pay me ANYTHING.

Don't worry Emu. Danny said the check is in the mail this time for sure.

... it's not?

I started playing the Najdorf (in rated OTB tournaments) when I was between 1300 and 1400.

Rating, I mean! 1300-1400 rating! I'm not quite THAT old.

Got my a$$ handed to me a few times, of course... but that's how you learn.

Depends why you like it. On one take, sure, it's enough that you do like it. As long as you are happy, what else is there? But if you are trying to learn chess...it would be more than ideal if you could say WHY you like it. And I'll say along similar lines "because I beat my big brother with it yesterday" is a poor reason (even though you might think it's an OK one). You should be able to say what each move does for your position, and why you prefer it to the alternative moves. Then, afterward, you find out this move order is called "The Najdorf." That's better (though still debatable) than deciding you like the name "Najdorf" or you heard it was complicated, or etc. Though if they make you happy, I will admit they are reason enough.

"studying the Najdorf Sicilian"

The Najdrof is one of the most theoretical opening variations in all of chess. Learning even half of the lines is an impossible task for a player of your rating, requiring a lot of time and effort. I myself refrain from studying such openings as the Sicilian as there are other areas of the game you could be improved. If you want to play the Najdrof, go for it. Learn a few short lines but don't expect to know the entire opening extremely well just after a few months of playing it.

"Any tips to Improve memorizing lines"

I would start by recording all the lines you want to memorize and storing them in a place you can easily access on demand. I use a lichess study, but I've heard other players use Chessbase to create their opening files.

Next you want to understand the position and the plans in that particular variation for both sides. This makes it easier to remember moves, as these general ideas can trigger you to remember certain moves.

Lastly, you want to play more games in the opening to build your experience and familiarity with the variations. This will help you remember the lines better, as you will get used to playing them in your games consistently. After some time, you'll know the mainlines like the back of your hand. The rare, tricky lines, though, will be harder to memorize. Analyzing your games in these lines to expose yourself to the right continuation as well as reviewing these lines using spaced repetition should help.

To study the Najdorf as Black, you would want to have something in mind to play against 6. Be2, against 6. Bc4, against 6. Be3, against 6. Bg5, against 6. f2-f4... there are a number of minor lines as well, such as 6. h3, or 6. a4; but the first five alternatives are enough for a start.

Here's how I play the Najdorf against 6. Bc4

In life commentary to the last World Championship Match, former World Champion Anand said something like: In a similar position Wesley So played this.
Thus

1. Anand does not know/remember the line
2. Anand recognises the pattern and remembers the plan executed in a game of Wesley So