If you're a spread player, you may have played on arrow keys before and you may have not. Add an arrow key setup, just in case, because it will be necessary.
Take any one of your spread files, go into the editor, press enter to bring up the menu, then apply "NoJumps" to it. Imagine there is a pad player playing your steps, who starts with his left foot on the left arrow and the right foot on the right arrow by default. Every time the player hits an arrow, he or she is going to move their right foot, then their left foot, then their right foot, then their left foot, and so on for every pattern you give them.
Thus, in a pattern like right-down-left-down-right, what the player is going to do is hit right with the right foot, down with the left foot, turn their body a little bit to the left and hit left with their right foot, hit down with their left foot again, and then turn their body back and hit right with their right foot. This can be expanded to more complex turns like left-down-up-left-right-down-left-up. Avoid patterns like right-down-left-up-right, because the player has to spin a full 360 degrees to hit that pattern.
This is not to say that your file shouldn't have jumps--it can, just be much more careful of how you place them, because unless they're at the speed of 8th notes on a song 170bpm or under they will be very difficult for the player.
"Why is it bad to turn 360 degrees?"
You don't know what the arrows right after it will be. When you turn 360 degrees, you will have to regain your balance a little bit, and while you're turning you can't see the arrows. Turns like left-down-up-left-right-down-left-up and left-up-right-left-down-right are some of the most awkward you can get without spinning.
"So, what about jumps?"
Jumps are substantially harder for a pad player than they are for a spread player, or even an index player. Jumps to a pad player are, essentially, like how you would regard fast, left-down-left-down-left-down trills. However, jumps are also points where the "no double stepping" rule can be broken. Having a jump that's left+down invariably makes the player double step, and it's very acceptable to do that. Keep in mind the distance that you have your player move their feet--a left+up jump that has a down arrow right after it makes them move their leg very fast, very quickly. It's fine to do that, just preferably don't abuse it if you can.
If you need an example of how jumps affect a pad player, watch this video and see how he is able to do the 16ths perfectly, but the jumps, which would be no different for an index player, are much harder for him.
"What if I mess up one part of the file and there's a double step in the middle of it?"
This is actually pretty easy to fix. Just select the double step with spacebar, press "end", press spacebar again, and mirror everything from the double step onward. This can be a problem if you have very specific steps, so if you want to un-mirror the rest of the song after it's corrected, find a jump like left+right and mirror everything after that jump.
Footnote: Play your works-in-progress with indexes. You can go ahead and make them with spread, but verify the "no spin" criteria with indexes.
Take any one of your spread files, go into the editor, press enter to bring up the menu, then apply "NoJumps" to it. Imagine there is a pad player playing your steps, who starts with his left foot on the left arrow and the right foot on the right arrow by default. Every time the player hits an arrow, he or she is going to move their right foot, then their left foot, then their right foot, then their left foot, and so on for every pattern you give them.
Thus, in a pattern like right-down-left-down-right, what the player is going to do is hit right with the right foot, down with the left foot, turn their body a little bit to the left and hit left with their right foot, hit down with their left foot again, and then turn their body back and hit right with their right foot. This can be expanded to more complex turns like left-down-up-left-right-down-left-up. Avoid patterns like right-down-left-up-right, because the player has to spin a full 360 degrees to hit that pattern.
This is not to say that your file shouldn't have jumps--it can, just be much more careful of how you place them, because unless they're at the speed of 8th notes on a song 170bpm or under they will be very difficult for the player.
"Why is it bad to turn 360 degrees?"
You don't know what the arrows right after it will be. When you turn 360 degrees, you will have to regain your balance a little bit, and while you're turning you can't see the arrows. Turns like left-down-up-left-right-down-left-up and left-up-right-left-down-right are some of the most awkward you can get without spinning.
"So, what about jumps?"
Jumps are substantially harder for a pad player than they are for a spread player, or even an index player. Jumps to a pad player are, essentially, like how you would regard fast, left-down-left-down-left-down trills. However, jumps are also points where the "no double stepping" rule can be broken. Having a jump that's left+down invariably makes the player double step, and it's very acceptable to do that. Keep in mind the distance that you have your player move their feet--a left+up jump that has a down arrow right after it makes them move their leg very fast, very quickly. It's fine to do that, just preferably don't abuse it if you can.
If you need an example of how jumps affect a pad player, watch this video and see how he is able to do the 16ths perfectly, but the jumps, which would be no different for an index player, are much harder for him.
"What if I mess up one part of the file and there's a double step in the middle of it?"
This is actually pretty easy to fix. Just select the double step with spacebar, press "end", press spacebar again, and mirror everything from the double step onward. This can be a problem if you have very specific steps, so if you want to un-mirror the rest of the song after it's corrected, find a jump like left+right and mirror everything after that jump.
Footnote: Play your works-in-progress with indexes. You can go ahead and make them with spread, but verify the "no spin" criteria with indexes.