The first issue I've got to mention, the one that comes up in nearly every book I read that describes women getting into or out of their clothes, even if they're generally well-researched, is closures on eighteenth century gowns.
The dress was a Robe a l'anglaise a la polonaise. It was a struggle to deal with the zillion hooks-and-eyes at the back of the stiff, tight bodice. I could understand how a maid had been indispensable.- Coronets and Steel, Sherwood Smith
Hastily, she struggled upright and pulled on her rumpled, still-damp dress, catching as many of the fastenings as she could. She couldn’t reach all the hooks and it must be gaping around her waist, but at least the garment wouldn’t fall off. George put on her cloak to hide her back and then followed Mr. Pye outside....
The lady's maid was fastening an interminable row of hooks on the sapphire sack dress George had chosen to wear.- The Leopard Prince, Elizabeth Hoyt (set 1760s)
The bodice of the dress fastened in the back in a clever new manner that made it impossible to see the ties that held it closed. The front was cut low, inset with a tapered gusset of lace that barely concealed the rise of her breasts and ended in a point at her tiny waist.- City of Dreams, Beverley Swirling (set 1730s)
The interesting thing about most fictional descriptions of eighteenth century women getting dressed is that they so often focus on difficulty. Either the woman independently gets dressed despite the difficulty, or her maid takes care of it for her.
The answer is simple: during the eighteenth century, gowns closed in the front. Until the late 1770s, women got dressed by pinning a stomacher to their stays, and then fastening the gown over it, either by pinning it or lacing it across the stomacher, which is quite possible for a woman to take care of on her own. Variations existed for riding and traveling dress, which might button up the front like a man's coat or waistcoat. The compere front of the 1770s, with buttons running down the stomacher, could be ornamental (an ordinary pinned stomacher decorated with buttons) or functional (with the sides of each piece of the stomacher sewn to the gown). By the end of the decade and in the 1780s, a gown could be fastened without a stomacher, the two sides of the bodice meeting in the center front and either pinning or hooking shut. Even with the rise of the high-waisted gown in the 1790s, it was still most common for some sort of front closure to be used, whether it was a bib (like that on an apron) that covered the pinned lining, or drawstrings along the neckline and at the high waist that gathered in the fabric and tied in the center front. Center back closures didn't become standard until ca. 1805, with the rise of Romantic style.
There are, of course, exceptions. French court dress (and probably that worn in other countries as well) laced up the back - famously, Marie Antoinette's gown wouldn't close in the back when she arrived at Versailles, and her pale skin showed through her shift. During the seventeenth century, the center-back laced closure was standard for wealthy women; the front closure over a stomacher used in the mantua was seen as much simpler and easier.
Children's clothing is another exception. All young children, until the age of six or so, wore gown which fastened in the back. Boys, just before they were old enough to be breeched, might wear coatlike gowns that buttoned in the front; girls might have a lace stomacher pinned over the front of their bodices.