Prepare to use Pay Per Click Heavily
Web developers must factor in the cost of Pay Per Click (PPC) when building a Flash site. A budget for this type of advertising must be included in the cost of developing the site, as it seems that the search engines may be getting better at reading Flash, they still don’t index Flash sites quickly, if at all. In fact, one AltaVista engineer reported that it wasn’t a priority, and had no intentions on including reading Flash into their search engine. Be aware, also, that Google’s AdSense officiallydoes not read .swf files. So in this sense, you may rely more heavily upon PPC than if you used a full HTML site.

Build an HTML site, and incorporate Flash later
Some web developers choose to develop a website in HTML first, then once they’ve established search engine positioning and PageRank, add Flash later on. While this sparks a bit of controversy in the ideology of this method, it appears that established sites that already index well who add Flash to their sites at a later date do not seem to suffer the same effects of a new site done in Flash. It would be a good topic of discussion in the SEO Chat forums.

Better yet, create a low-res HTML version of your Flash site, and let the users choose their preference. That way, you have the best of both worlds: a Flash site for the visitors wanting the glamour, and an HTML site for the search engine spiders and for those visitors on dial up.

Using CSS Layers
A method I have seen used is creating invisible layers in CSS, which can place invisible text over the Flash text, readable by search engines, yet not appearing to the human eye. I will caution strongly against this method, as I believe it is very similar to cloaking. However, the controversy arises because while cloaking is presenting one set of text information to visitors, then another to search engines, the search engines can detect this type of practice as spam, and the likelihood of banning exists.