Remember that most of these are just suggestions. You don't have to do the alignment stuff in blue, but it will probably make the map look better. More important stuff is in red.
You need a preview point. Go to Timing --> set current position as preview
Most alignment things can be fixed by holding shift while distance snapping is on, and the editor will automatically align things perfectly for you.
You can also stack things directly on top of each other by setting distance snap to 0.0x, turning off grid snap, and then moving it. This will put it exactly on top of the previous object. You can stack slider end points by first reversing the slider (ctrl + R), then using the 0.0x distance snap trick, then reversing it back with ctrl + R like it was before.
Easy:
00:41:14 (1,2) - Align these better.
00:42:69 (3,4) - ^
01:15:40 (1,2,3) - Ugly. Lower stack leniency, then turn off grid snap and distance snap and stack everything better.
01:35:43 (1) - Move forward 1/4, then make it 1/4 shorter
Hard:
Lower overall difficulty by 1-2 ticks.
00:19:66 (3,4) - Stack endpoints better
00:20:43 (5,6) - ^
00:37:47 (6,7) - Align better
00:41:14 (1,2) - Align better
00:42:69 (3,4) - ^
01:23:92 (3) - Add repeat
01:26:24 (1,2) - Align better
01:31:66 (9) - Stack with 8 endpoint
01:35:53 (1) - Move forward 1/4, then make it 1/4 shorter
01:41:69 - Move this inherited section back 1/4. The hitsound will sound wrong if the person clicks too early.
01:54:69 - Move this inherited section back 1/4. The hitsound will sound wrong if the person clicks too early.
02:26:63 (3,4) - Stack endpoints better
02:27:40 (5,6) - ^
02:28:18 (7,8) - ^
02:35:92 (1,2) - ^
02:45:21 (1) - Move forward 1/4, then make it 1/4 shorter
Insane:
00:14:79 - Add circle here
00:19:66 (3,4) - Align better
00:20:43 (5,6) - ^
00:24:02 (10) - Sound better if you remove this
00:37:47 (7,8) - Stack endpoints better
00:45:98 (1) - This slider goes off the grid. Don't do that.
01:01:47 (7) - Random same-combo jump. Put a new combo here to warn about the jump, or move it closer to the 6.
01:01:47 (7) - Also align this better with the 6.
01:11:92 (5) - Move this so it's exactly on top of the 4 slider repeat.
01:20:82 (1,2) - Align with the 3 slider endpoint.
01:25:08 (8,9,10) - Stack endpoints better.
01:35:53 (1) - Move forward 1/4, then make it 1/4 shorter
01:41:69 - Move this inherited section back 1/4. The hitsound will sound wrong if the person clicks too early.
01:54:69 - Move this inherited section back 1/4. The hitsound will sound wrong if the person clicks too early.
01:51:02 (1,2) - Align better.
02:04:56 (6) - Stack endpoint better.
02:20:34 (4) - Sounds better if you remove this.
02:24:69 (6) - Stack on 5 endpoint
02:32:73 (4) - Sounds better if you remove this.
02:34:24 - Add circle here?
02:45:21 (1) - Move forward 1/4, then make it 1/4 shorter
