In the SF bay area it's pretty easy to grow avocados. There are a few important things to know: 1) the types of Avocado and 2) growing conditions.
1. There are three general types of Avocado tree -- Mexican, Guatemalan, and West Indian. Guatemalan varieties are the kind most people
(at least here in California) are familiar with -- they're creamy and rich. Mexican varieties are smaller, with thinner skin (sometimes edible) and sometimes are good tasting. West Indian varieties are large and watery. Guatemalan trees are very frost intolerant while Mexican varieties are more frost tolerant (for example, the Mexicola variety can handle down to 22 F). Nobody in California grows West Indian varieties.
Avocados don't grow true to seed, so growing it from a seed (unless you plan to graft it yourself) isn't really worthwhile. So buy a grafted tree from a nursery. If you live in a part of the bay area that's coastal and has minimal frost (e.g. East Bay from Fremont to Richmond, San Francisco, San Rafael, etc.) then a Guatemalan variety is a good bet -- Reed is a good choice, as is Lamb Hass, Hass, Pinkerton, and a few others. If you are in a less coastal area, one that gets more heat in the summer and frost in the winter (like San Jose, Palo Alto, Morgan Hill, etc.), a hybrid Mexican-Guatemalan variety like Fuerte is a good choice. If you're in a spot that gets a lot of frost (like Santa Rosa, Napa, Petaluma, etc.), then go with a Mexicola.
2. Avocados like a mostly-sunny to sunny spot, with as little frost as possible (so not in a low spot) and in a spot with good drainage. They don't really fruit in containers, so it's not worth trying that route. The best approach is to dig a big hole to loosen the soil but then just push the soil back in, and plant the tree so it's about 6-12 inches above the natural soil grade. Heavily mulch
the mound with tree trimmings and leaves and such, and keep any weeds or grass or other plants away from the tree. In the summer the trees can be watered 1-2 times a week -- deep waterings are best. In the winter there's no need to water -- the main danger is root
rot if you have bad drainage. As the trees mature you can water less frequently.
Some people talk about the need for cross pollinators -- this is more true in Southern California and Mexico. It's not that important in the bay area. Reed is known as a good self-fertile variety, but most will fruit without another tree here.