From the Site FAQ (link in the panel on the left):

"New users are only allowed to sign up for five swaps at a time until they have received three "5" ratings from their swap partners."

Although that is when the 5 swap limit will be lifted, individual swap hosts use their own criteria for who still counts as a newbie, so for some of them, you may still be a newbie for quite a while after that.

Put the swaps you want to join that occur later on your watchlist.

Yeah, i've done that too, but can only "watch" about 5 before i keep getting a message saying i cannot join any more!

While you are signed up for 5 swaps for which you have not yet pressed Sent, you can no longer add more to your Watch list. If you keep your number of swaps to 4, you will be able to add as many as you like to your Watch list, I believe, so just drop the one with the latest sign-up date and rejoin later. The admins are aware of this glitch and will fix it eventually.

Ahhh...i see! Thanks for that!

Signing up right before the sign up deadline is essential because if you are signed up for one that won't start for weeks or months, it's just tying up a slot that you could use for quick ones.

People host newbie specific quick swaps from time to time. They are usually called "fast", "overnight", or "ratings boosters". There are also established swappers out there who are willing to do one on one swaps with a newbie to help them get their ratings up.