if you have questions about what you like, go to a plus size store and try things on. they may not fit right, but you'll have an idea of what you feel looks good on you. then find the closest, easy pattern. a flared skirt is the easiest garment to fit and sew, and a tunic top with no darts is simple and easy to wear on top. you can even find a pattern that has sleeves built on instead of having to cut the sleeves separately. read the measurements carefully, especially about the 'high bust' or chest.
take it one step at a time. plan before you start. have fun choosing fabric. if you go with a dartless top (i would begin with one), choose a knit for easy shaping. finish off your top above or below the widest point of your hips depending on your height. keep the style simple. if you're short, stay away from too much fullness at the sleeves, bust, waist or hips. down at the hem is okay. nothing tight.
a 2-pc is often better than a 1-pc if the top is longer than the waistline. don't wear a belt. wear long necklaces or earrings if you wear jewelry. they light up a simple shape. no big, lumpy brooches, however vintage they are. no big flowers. no big anything. no tiny anything. simple, simple, simple. if people don't remember how it fit you, it fit right. bright colors on top, dark below. every woman looks good in pink (old but true).
if you want a dress, stay with the tunic top made longer. choose it by the top size, according to the measurements on the envelope. if your hips are large, simply widen the side seams out until they're full enough to fit around your hips + 6" ease. you have to sit in it after all. definitely stay with knits, but a firm knit. after you decide on the length, create side slits if there aren't any. you need that for walking ease. if you need help, borrow a beginner's book from the library or a 4H club. there are wonderful books, and well-written with great pictures.
if you need help or more ideas, pm me.