I'd echo the previous suggestion of 500 pieces, if you're daunted by 500 pieces. Ravensburger are good quality and have a huge range of images in 500 piece puzzles, which not every brand does. If it were me, I'd go for one of the Circle of Colour puzzles, because the round shape is interesting and the gradient should help you.
For me, image type matters more than the piece count though. The 1000 piece gradient animal puzzle took way less time than the blue 500 piece puzzle, because with the gradient it's easy to tell where a piece goes in the puzzle just by colour, rather than having the same colours all over the puzzle. Generally bright colours, gradients, and distinct sections which have clear patterns, colours or textures to be able to easily separate make a puzzle easier, and large sections of the same colour are best avoided. I haven't done them, but Ravensburger have New York or London Postcard puzzles in 500 pieces and they are always considered the best puzzles to get at the Jigsaw Puzzle World Championships.
I generally pull the edges out if it's a puzzle where that's helpful, along with a few other distinctive sections and then place the other pieces face up in the bottom half of the box, laid on top of each other. Then when I've finished with the pieces I've pulled out, I'll comb through the box to pull out other sections. Or if I feel like it, I might do a full sort where I pull out all the pieces into different piles. Depending on your space with a 500 piece puzzle though, you might be able to get away with just spreading the pieces out. On my puzzle mat, I can get the pieces laid out in a mostly single layer, so I don't sort properly as I can see all the pieces at once.