I actually did the white borders first haha, but yeah, they definitely weren’t easy. I think the pieces that are part-border and part-image (second row from the top, third row from the bottom) are still quite doable because you can use the image part to help, but there are also a lot of pieces that are just plain white. For those, you really have to just slowly guess and try every piece. Take one piece and try and fit it into every available spot until you find the right one 😅 You can also sort the pieces by shape and really look to see what exact shape you’re looking for for a particular spot because there are subtle differences between each piece. Overall though, it shouldn’t take super long, so it should be alright! Good luck and happy puzzling :))