You should not worry about the Google Page Rank system that is zero to ten. A website that has a rank of 5 could have been a 2 last year. A website with a high rank could also be sold or dumped in the future. I am more interested in the actual website and if it is up to date. Does it look like it will be there next year?
You should gradually get incoming links from search engines (Google, Yahoo, MSN) and directories (DMOZ, for your location, about your topic). And gradually exchange links with other websites that advertise products or services in your location or websites that are about your topic but not direct competitors. Do not bother with paid listings in directories. You can also post links in forums as long as you don't spam. And post articles or press releases that contain a link to your website for more incoming links that do not require a link back.
You can link to websites for example real estate insurance, real estate loans, title insurance, landscaping services, construction or home improvements in your location. This would help your visitors as well as search engines. You can also link to other real estate websites that are in another state or country. I have a client who sells real estate in California and another client who sells insurance in California. They are both in the same area and would both benefit from a link exchange.
The best links are from websites that are already listed on Google. You should not add links simply to improve ranking and add them to pages named links1.htm, links2.htm. There shouldn't be too many links on a page. I tell people to limit them to 20 per page. The links should be organized and appear on "regularly viewed" web pages whenever possible. Also try to get people to link to specific web pages and not just your home page.
On my website, I have pages about graphics and link to graphics software or designers from that page. There are articles that include links to topics mentioned in the articles. It is important to link to as many pages as possible from your own web pages and other web sites for better results. Most people don't follow this advice and simply help their home pages!