Strata is challenging because you have to place the colored lines down in the opposite order from which you work out where they should go. If you can remember or write down what you work out and reverse it, then it's easy to do. However remembering is hard if, like me, your brain is rubbish, and writing down your thought process takes far too much effort.

Instead these puzzles can be solved with a two step forwards-only method. The first step is to find the right starting point, and the second step is to use that to solve the puzzle.

To find the starting point we want to cross out all the parts of the puzzle that aren't the starting point. For this step we only care about boxes that have NO lines through them. Ignore any single-lined or double-lined boxes.

The rule for this step is cross out and ignore lines of the same color until not much is left.

Example puzzle:



There's always a starting line which is made up of boxes of all the same color, with or without empty boxes. The four red boxes here clearly fit the ticket, so they are the first to cross out. Slap a colored line through them (don't worry about matching their color).



Great. Now, whilst ignoring those red boxes we need to find another line of same-colored boxes. The orange boxes intersecting the red ones qualify, because we don't care about the red one.



Following the same rule, the pink and dark purple boxes form lines, so strike them off.



After all this, we're basically left with a 3x1 set of untouched squares (orange, purple, light blue). This is our starting point, so quickly remember it and hit restart.



The starting point is not always 3x1, it can be 2x2 or 1x2, or basically any small set you are comfortable with.

After restarting, solve the starting point. From here, we want to put all the rest of the lines of the puzzle in place and solve it. Here's our example with the starting point solved:



The first thing you might be panicking about is colors, but don't worry. They are obvious. In the above image, the lines on the left side will clearly be pink, red and dark purple respectively and the line on the right side is going to be orange. Any other color for these lines would cause an invalid solution.

So the only question left is 'what order do we put them down in?' The rule for that is place lines if all of their colors are already intersected. Intersected meaning they already have one line through them. There is a caveat, which I'll talk about later.

In the above example, the pink and dark purple lines are both good to place as all the pink and dark purple squares are intersected. The red line is not good because one of the red squares isn't intersected. The orange squares are definitely no good because two of them aren't intersected.



Once the pink and purple lines are filled in, we can have another look. The red line still has an unintersected red square, but the orange line is now good because all three of its orange squares are intersected.



And now the only choice is red.



Perfect. Of course this is more or less the reverse of what we did in step 1, but the point is you don't need to remember and reverse it all in your head.

The caveat I mentioned earlier is that you can ignore a colored box if both the lines which go through it are the same color.



In this example, the red box that isn't intersected is not important, because both lines going through it are red. It can be ignored, and both red lines are good to be placed.

Here's an example of a 6x6 puzzle. If you know what you're doing, you can solve this in under a minute.



First thing to do is block out lines and figure out the starting point. Here's what I got:



Now restart and solve the start point:



On the left, the black and green lines are the next step. Both of these are tricky, because they have unimportant boxes. Remember, a box is not important if both the lines going through it are the same color. You can ignore those ones.



Both the black and one of the green lines on the right are complete and can now be placed:



Now these two royal blue lines can be placed. The intersection between them would be a non-important box, but it's empty anyway.



From there, we just need to place the red on the edge, then the remaining green then the red and we're at the goal:



Hooray!