Putting together a BJD is a tricky task even for the experienced hobbyist, not to mention novices. If you buy a Forest Dweller you could just enjoy a tiny animal as is. But if you plan to buy a mature head from me you need to choose a proper body, to find a makeup artist or paint the face by yourself, to pick right wig, eyes and clothes. This info could help you a bit.
I sculpt my molds in a way they could fit on a several bodies of other BJD manufacturers. Some people would like a lean character, others - more broad and muscular, so choosing a certain body would help to create the character you want. Every mold has the info on suitable bodies, and as customers provide hybrid photos I add them to the page.
My animal dolls can wear a simple glass or acrylic BJD eyes, required diameter is listed on the page of each doll.
My head molds take 8 mm eyes: they provide the most realistic look. The best eyes that are both great looking and affordable are Pabol oval glass eyes, that are sold by several dealers, such as Kemper Dolls or Blueberry Style.
It's much easier to choose a wig for females than for males. I'm often asked where I've got those short wigs for my male dolls. I made them by myself, and you may try my tutorials if you wish:
Meanwhile look at those sites which have a plenty of wigs:
Luts - nice wigs, some are short,
Dollmore - the same,
Alice's Collections - the same,
Monique - lots of epic female wigs. Their photos don't do them justice.
There are wigmakers on Etsy who either have various wigs including short wigs in stock or even can do custom wigs: Sophy Molly, Blueberry Style, Sophie Toy Paradise.
You can buy a short wig for your male doll and cut it even shorter.
While choosing a wig please pay attention to the size: it's mostly specified in inches.
The task of finding a faceup artist is tricky, as the whole makeup thing is very subjective. Usually I don't offer a separate faceup services as my time is dedicated mostly to making a new dolls and customizing mine. Though I offer faceups for my own molds, on request.
Lot of faceup artists offer their services, but the best artists are often busy, and their services cost a lot. So the first thing you need to figure out is how much you are ready to spend on the faceup. The second important thing is a desired style: an artist who tends to paint a sweet lolita girls with feathery eyebrows and glamourous boys with glossy lips most likely wouldn't paint a brutal character with a beard. Begin your research having that in mind.
How to find an artist? Try asking Google, as it's our best friend!
Once you've found several faceup artists which style you like ask them if they are open to commissions, or wait for a slot.
What fits a certain body highly depends on what body you choose for your head. Some bodies have a lot of clothes and shoes to fit on, other ones have less. Usually the company which sells bodies has some clothes in stock, but not always. The general rule is to know the measurements of your doll body and to research the market: you can buy clothes that fit the bodies of a similar size. Usually 1-2 cm is not a problem. If you like a precise fit your option is to sew or commission though)) I never bought nor clothes neither shoes for my dolls, as I make everything by myself, and was obsessed with a proper fitting, but when I was able to dress 70 cm high FaCo Doll body into the clothes and shoes made for 65 cm high Soom Supergem body I became much less skeptical about fitting.
You also can ask owners of the same bodies where they shop for BJD clothes: many people willingly share this info.