You’ll need to use a different e-mail address each time you complete an offer. (Switching between 2 emails does NOT work)
This will help to increase your approval rate.

When you join any offer you will most likely enter a email, this email is what the advertiser will use to identify you as a new sign up, if you complete an offer from the same advertiser again and enter the same email you will NOT be approved again so use a NEW email when completing offers from the same advertiser/ offer group and you will get approved more.

To create emails you can use any of the main providers such as Gmail, Yahoo, Hotmail, Inbox etc, Also if you own a website you can use your own personal brand of emails (Example@Points2shop.com) however this is untested in approval rating.

TEMP EMAILS ARE NEVER ALLOWED AND WILL GET YOU BANNED IF YOU USE THEM!
Temp Emails are just temporary emails, They are created randomly and have a lifetime of 15 minutes before they are deleted, these are not allowed on offers and will get you banned and your offers earnings reversed, so don't use them

Its recommended to create a new email every few offers you complete, Just make sure you don't complete an offers from the same advertiser or offer group twice (UKPD or ES for example) and you should be fine.