I settled on double pips
For the indices, double pips are redundant. You want to have as little out in the index as possible, because every square centimeter that's used by the index is space where you can't fit your art or have adequate negative space.
The reason most indices have pips below the ranks is that when you hold cards in your hand, squeezing them together to just show the indices, you can get them closer together if they are stacked one on top of the other, rather than side by side. The more you have to spread your cards out when holding them in your hand, the greater the chance that someone you're playing against might spot what you're holding, even if by accident. Ranks are usually placed above suit pips because in most games, the rank is more important most of the time - for example, in poker hands, only the flush and the straight flush are in the least concerned with the suits of the cards you're holding, while all the other hands are only concerned with rank - and the straight flush requires both the suit AND the rank, meaning only one hand completely disregards rank.
Consider this when looking at your design. Remember that, like any rule of design, you can occasionally break them - but it's best to know why, and to have a really good reason rather than to do so by accident. Otherwise, your work might end up appearing amateurish.
Also consider something else - contrast. You have a very, very dark background - granted, your images are black and white right now, and I'm guessing at some point they will be in color. When that time comes, you'll need to make your artwork very, very bright to adequately stand out from such a dark background - if there's inadequate differentiation between the colors, your art will get lost in that black background and look muddy and indistinct. I've seen some potentially great designs completely ruined by a poor choice of colors.