I wouldnt worry about these tags too much they dont carry much weight anymore, just tag them sensibly and dont stick 15 keywords in there as it wont help ! Woc
Not sure what you are asking if you are wondering how to technically do it or if you are looking for suggestions - use keywords!
try to put your major keywords in alt tag.......it will help you out to increase the keyword density...
I think he is write and you can use google keyword tool to get some more keyword related to your topic and you can try them too .