If you are running an adwords campaign and one of your payment methods is direct paypal in your domain and facing difficulties to track the adwords conversions, below source of info/process will certainly be helpful to overcome the issue.
What you need:
1) Must be using
analytics universal tracking code.
2) Paypal must return the customer to your domain once payment has been completed.
3) Adwords conversion tracking code must be installed in the success.html (example) page to track the conversions.
4) Now begin the process below.
Make sure you add paypal.com in the 8th step. This will help you to exclude the referral traffic from paypal via (after payment) conversions and append the visit to success.html to adwords transactions/conversions. Paypal Referral Traffic Exclusion process will greatly help you enable the conversion optimizer to your campaigns in adwords and get more accurate analytics data.
Hope this helps.