1. Salwar suits are like air-conditioners, they can be made to adjust your body type. Depending on the fit, they can make you look slim or plump. Basically, salwar-suit makes a woman look slimmer and shapely.
2. If you are a bit on the bulky side, choose fabrics like soft silk, crepe, soft cotton, linen, georgette. Polyester or chiffon would hang away from your body making you look bigger. Silky fabrics that cling just a bit, are a good choice for you.
3. Also fabric blends with spandex; lycra like stretchable fabrics should be chosen very carefully, as they will tend to stick to the curves of your body accentuating them in bad manner.
4. If you are too slim and would want to add some volume to your figure, go for heavy silks, jute, thick cotton, spandex blend cotton. You can do ok with chiffon and polyester too.
5. Avoid sleeveless, deep neck or open back designs of the top, if you are heavy. Flesh protruding out of the dress is not flattering.