You have a nice boat but a 20 footer is really marginal for the waters outside the golden gate. Actually the SF bay can get quite nasty when the winds come up and they can come up quickly. I was coming back from an ocean salmon trip in a 28' Trophy and the waves in the bay were so bad we didn't think we would make it to the marina.
When going out in the ocean you have to look at weather forecast, wind and swell. Bottom line go when the wind is minimal, under 10 mph and the swell is small under 6'. You need to look the the time between swells. A 6' swell at 14 seconds is pretty mild but a 6' swell at 7 seconds would be bad, may swamp your boat. The critical thing is not just the size of the swell but the timing between swells. I wouldn't venture out more than a mile or 2 until you have experience and know what you are doing. Watch the winds carefully . I've seen the wind go from 2 to 3 mph to over 20 mph in an hour.
One piece of safety equipment I think is essential when in the ocean is a VHF radio that is integrated with a gps. In an emergency at the push of a button your VHF will send out a distress signal along with your gps coordinates.
When you go outside the gate you will run into an area known as the potatoe patch. The potatoe patch is always rough, your boat can take it but be prepared for this patch of rough water.
The following is part of a discussion I was involved in years ago which I think you will find quite helpful.
As others have said, you are off to a good start by asking questions. Guys like you, who come to the ocean with an open mind, a desire to learn, and humililty become the best skippers. Conversely testosterone and macho get people in trouble.
I don't relate boat size to conditions. I would use the same go/no-go criteria for an 18 footer as a 22 footer. Of course when you get up to around 26 feet and larger, there is a difference there, but not so much for smaller boats.
Six feet is the maximum swell I usually go out in. And it all depends on the period (number of seconds between waves). A 6 foot swell with a 13 second period is a long rolling swell that is quite doable. But 6 feet at 6 seconds is a beastly sea with waves so close together you slam from one to the next. As an aside, 6 and 6 is called a "square" sea because the size and period are the same. Similarly, a 7 and 7 is also a square sea. Square seas are miserable at best, dangerous as worst.
Now let's look at a 6 foot swell at 9 seconds. This is a doable sea, not especially pleasnant, but doable. However, I would not go out in it. The reason is it is a steep sea which gives the wind lots to push against. If the wind comes up, it gets rough very quickly. 15 knots of wind makes the swell higher and the tops start to foam. So while 6 and 9 is ok with no wind, it is so vulnerable to a blow that I would not go out in it.