I'm giving the Sumo stance a try due to my wider hip base, and I feel my technique is not that great.
I'm placing my legs just inside the ring and pointing my toes to the tip of the plate.
Post up a video of yourself if you can. Otherwise make sure your shoulders are behind the bar, push your knees out to the sides, look straight ahead, spread the floor and try to bring your hips into the bar.
A video is needed to give you any kind of specific advice. Echoing what has already been said, some useful cues are knees out, chest up, arch hard, and pull.
You're feet should be as far out as they can go without sacrificing speed in the pull. For me this is about the width where my shins touch the rings while standing up straight.
Air up your belly before you bend down to get to the bar. Hold a tight arch in your lower back. The extend your arms fully with no bend in the elbows, pull the bar backwards towards you, (pulling slack) then drive with your legs and continue pulling back. You should feel most of your weight on your heels, if not you need to adjust. Additionally the sumo dl is difficult on the hip flexors so it may take time to move your stance outward. Foot positon is also key, if your hips are tight you will likely have to angle your toes outward, ( duck toed) to get into position. I have noticed many new sumo pullers have a problem of sitting down too much before they begin the pull, if you are arched, tight and have the bar tight against you there is no need to sit any deeper.
Thanks guys, I'll post a vid after my next dead lift workout on Monday.
Just did our max effort dead lift last night. Pulled 225x5 (warm up), 315x5 (warm up), 405x3 (warm up), 455x1, 475x1, 495x1, missed 515.
sounds like you did ok. What is your best conventional deadlift?
Things that I've learned that help my guys a lot are as follows.
1: Play around a bit with your stance. Watch vids of lifters with somewhat similar proportions to yourself. Once you get that straightened out...
2: Knees out hard.
3: To be somewhat crude, try to put your balls on the bar. That goes in line with #2, knees out hard. This will build tremendous tightness in your hips.
4: Low back arched hard.
5: Chest high. Not head high, but chest high.
6: Hard one to explain, but you have to sort of flex your hips to break the bar off the ground. If you're trying to put your balls on the bar, and your knees are out very hard, you'll find that it's not so easy to reach the bar. If you can hold this tightness it can result in very good explosiveness off the bottom, which is normally the weakest part of a (raw) sumo pull.
I'm not a good conventional deadlifter, and less so for sumo, but incorporating some of the above things got me a 545 pull last time I tried, and I believe I had another 10-20 or so in the tank.