the most important part to keep your shoulders from rounding forward is to always remember when rowing or doing a back exercise...push your sternum out. it will make sure youre getting a maximum squeeze. also, if you cant do a row (for example) and hold the weight, its a sign you arent using the contraction to lift the weight, so go heavy, but be sure youre lifting the weight, not throwing it, swinging it, etc.
"Abs on a skinny guy are like big boobs on a fat chick - they don't count." -Shelby Starnes