If you are in a big sales team and sometimes get a little flack from your fellow salespeople then take heart at what Dale Carnegie had to say:
1. Remember that unjust criticism is often a disguised compliment.
2. Do the very best you can.
3. Analyse your own mistakes and criticise yourself.
4. Ask others for constructive criticism.
If you are making major sales in your own business or in a sales team the best thing to do is be your very best. If your company does not provide any form of sales training (most do product only training) make sure you do it yourself. Read all the books by Neil Rackham and practice what he preaches. Making major sales is a completely different skill from making simple sales and the more training you do the more skills you will aquire. That means in the end the more money you will make. Once you become a true professional salesperson the world is your oyster.