I've always been all for cohesion in wardrobes and recently I came up with a theory for simple but easy coordination, so I thought I would share my thoughts.
When it comes to wardrobe building, I rely mostly on colour. It's very simple actually, I have two neutral colours and then a matching colour. For me this is white and cream matched with pink. As far as I am concerned, main pieces can be any colour that matches pink (including those three colours) which culminates in my one rule- does it match pink? If it doesn't, I will usually reconsider it.
I think for the most part this kind of thinking works best for building Sweet wardrobes, since that's all I really have experience with and of course this won't work very well if you like to mix up styles a lot! But if you're interested in building up a small cohesive wardrobe without too much excess (at least to start with!) this is has been a good strategy for me.
As for my simple and easy coordination theory here it is: match your blouse/top to your legwear in colour, match your headwear, accessories, bag and shoes to each other in colour. Make sure your theme matches- and that's it! A cute and cohesive coordinate. Sometimes it might not be the most interesting coord, but I think 'boring' is a pretty poor insult in the scheme of things- especially with many girls complaining about the costumey nature of lolita lately.
For my example I used cream and white (my neutrals), pink (my main colour) and lavender (just something a little more interesting). An interest colour like lavender isn't always going to work with everything spectacularly, especially if the colour isn't in the print. It doesn't hurt to experiment a bit and if you use a colour that goes well with your main colour (in this case pink) I think the colour will still work (it's just going to look better in some cases than in others).
I used the same accessories for all the coordinates, for ease and to keep things consistent. Everything is pink- this helps to make sure that you aren't top or bottom heavy in one colour or another. Having the legwear match the blouse means that colour appears on both your top and bottom. With each of the accessories matching each other in colour, you ensure that the colour appears balanced throughout the coordinate.
I used three different coloured pieces from my wardrobe for this example. First up, Magical Etoile in pink! The lavender worked so well in this coordinate. I think this is due to the fact that pink and lavender go so well together, as well as the fact that the accessories are pink. When using a more interesting colour, I think a two colour palette works best to make the interest colour pop!
Second is Rose Toilette in mint! This introduces a third colour to the scheme when using our interest colour. Because the pink occurs in the print, the accessories work well when paired with the two neutral colours and pink. However when the lavender is used, the three colour scheme is more obvious. I think it's actually quite cute together, and it still works, but it might not be everyone's cup of tea.
Finally Jewellery Jelly in sax! The neautrals and pink are quite straight forward. As for the lavender, iIn this case, there are little spots of lavender in the print and the lavender works well with that. Three colour coordinates can be difficult I think and in most cases I think the more unusual colour might be better utilised for the accessories than for the blouse + legwear but without a doubt the coordinate is still cute and works well.
I think that this simple sort of idea works well for making cute colour coordinated coordinates but I think introducing a third colour into a coordinate can make things more difficult, especially if you're a beginner. Using an idea like this can make sure it still at least looks cohesive and balanced, I think! Personally I think I prefer sticking to two colours because I think there is something elegant in simple- like having big spaces in a clean room. Very satisfying, haha. I'm not big on mess in my environment, so I don't want to wear an outfit that feels messy to me.
Well, anyway, those are just my ideas. This is all quite basic, and I don't know how useful they are but it was a fun exercise- to be honest I probably wouldn't have paired the lavender with these pieces before this but, it's turned out really quite cute! There is of course a lot more to coordinating than just colour- theme and style are also important but if you've been reasonably strict or limited with building your wardrobe (like I have) things will usually match quite well regardless, I've found. And of course, what about patterned legware? Well, matching the accessory colour will be easier than matching the main piece colour, I think.
Thanks for looking~