Hello and welcome to RepGeek!

Maybe you need to read a bit more but you aren't supposed to put anything on the comment box when paying through PayPal. To do so puts a huge risk on both you and the seller. Initially I would recommend you use the trusted dealers (what we refer to as TDs) for your watches. Although not all of them use PayPal, you can use other payment schemes for those who do not. Make sure that the site you are ordering from is the correct one (there are some who prey on the popularity of these dealers by using similarly named websites) and they change site names quite a few times. The additional advantage of using trusted dealers is that since these are vetted by the forum management, they will be able to assist you in the rare case that a transaction needs their attention.

After you get more experience with the forum and the members, you can then do M2M (member to member) sales although there are members who have a high feedback rating which is a good measure of the member's trustworthiness. Still I would stick to the trusted dealers unless you see a very good deal come up from a high feedback member. YMMV. Enjoy your stay!