The way I started (less than a month ago) was just to pick some recipies from the net, order the flavours, and make it.
I also ordered a bunch of flavours that I thought were interesting, but that has turned out to be a bit of a mistake. Better to choose a recipe and look for flavours than to get flavours and try to find recipes.
I think CAP and TFA are the best flavours, but I'm sure others have their favourites.
I'm now just going through "the big TFA recipe thread" I found on reddit and have been trying out the recipies there, and every one I've done so far has turned out as good as any juice I've bought.
Another thing to avoid is measuring with drops. Better to get a 1ml syringe and be accurate. With some flavours, being just a few 1/10ths of a ml off can ruin it.
Oh, and be patient. There is no way to rush steeping time. Most of the recipies I've done so far are pretty disgusting right after mixing, but after 4-5 days turn into something completely different and awesome.
But really, the best thing to do is read, read, read. The stickies at the top of the DIY section is where you should start.
DIY E-Liquid