Style.
No matter what your shape or height, if you are a large lady a clean line will work best. Forget all the frous frous, bows and gewgaws a little can look great as an accent, but you are aiming for clean lines.
Gypsy skirts are out unless you are a tall banana or apple. They look great on some people, but for the shorter ones and the hip heavy they will accentuate you worst assets.
A - line skirts and dresses and fitted straight leg pants are where you want to head. Asymmetrical hemlines are also a great way of shifting the eye from trouble spots
.
Three quarter length over garments will make you look more slender, rather than jackets and bolero style tops.
Try using assymetrical waistlines to draw attention from your hips, waist and abdomenal region.

The effect is similar to three quarter oner garments; making you appear taller and therefore more slender.
Patterns
This is one of my biggest gripes at the fashion industry making clothes for women my size. What on earth possesses them to think that large women are going to look wonderful in big, bold florals, horizontal stripes and retro patterns? Generally they have the effect of making us look like an overstuffed couch.

Clothing or Couch?
Please stay away from these fabrics. If we don’t buy them maybe they will get the message.
If you want to wear a pattern try a small pattern that runs on the diagonal or vertical. It is much more flattering to most women with curves. An all over print can camouflage figure problems, but prints here and there can create a fuller you.
Thicker vertical lines in checks and tartans lengthens and slims. Knitted textures, lace, florals, prints, and tartans can assist in creating an illusion of narrowness if used in the right places. Be careful with tartans, that the bolder lines run vertically. Play safe and use the design on a diagonal.
If you want to wear printed or patterned fabrics wear a larger print where you want people to look and smaller print where you do not want them to look. Prints around the neck and over the shoulder can make your shoulders appear wider. Just wear prints near your figure's assets, because they are usually more eye catching than a solid colour.
Lines.
As an artist I have learnt that lines are a great way to draw the eye to a particular part of a painting or away from it, as in a horizon line or a water line etc. This also works in clothing.
Think about where the waist line is. A horizontal waist band or hem will accentuate your waistline; often an area we don't want to emphasize. Here's the same model in two different outfits.

A Horizontal waist band accentuates the hips.

The same idea with no waist band, on the same model,
looks much slimmer.
If you wear a white top and black pants for example the eye is immediately drawn to the end of the white and the beginning of the black. Your question in this instance should be, is that where I want people to look first?
Don’t get me wrong here, I am not saying you can’t wear two colours. Just be aware of where one colour starts and other stops. The trick here is that the line also acts to accentuate that area by making it appear wider. So a white top with a straight bottom that finishes at the widest part of the hip over a pair of black pants, is going to make the hips look wider than they are. This is great if you are an apple shaped lady wanting to create that balance, but not so good if you are pear shaped.
Tops and bottoms of one colour will make you look slimmer. Try a pants or skirt set with the same coloured top as bottom and maybe throw a colourful duster jacket or similar over the top,
For the bananas amongst us, curvy lines especially ones that curve inwards in the waist area are great for creating that illusion of curves where none may exist.

Inward curves make you look more slender, giving the illusion of a waistline
where none exists. These two garments are on the same model.
Your body can be shortened,lenghtened, widened and narrowed with seam lines, belts, bows, and collars. Be very careful where and how you use these things.
As already discussed tight tops with short or no sleeves and breast pockets are detracting from your figure. Lose the breast pockets. You are aiming for a clean line. Ruffles can also detract rather than add to your look. If like me you have heavy upper arms try elbow or three quarter length loose-ish sleeves