spam alt img with keyword

when I browse several web design site, I found several website use in their alt image using tag title="their keyword". is it safe or not?

No this is usual now and not spam.

Of course, putting too many words in there would be bad.

How many words are save to put at title tag and search engine assume not like spam??

the words in your title should match your content and 3-5 words is good for you .And i used to optimize my sites with WebSeo,through scanning your site ,this tool will give you a expert report that how to optimize your site title ,site url.It aslo tell you how many words you should put in your title and how many keywords you should put in your single page.

The most important is you put your keyword in the first 3 images of your pages... and thats it.. but remember that dont repeat to much..

why first 3 images only? doesnt make sense

Which one that I must do? first 3images only or all images that I use in my website? If I use some small icon in my web, should I use alt img with title or just leave it blank?

alt tags should be used for describing the images-not stuffing keywords. Besides, if you think that it's going to have an effect on your ranking then you have a lot to learn about SEO still. You should drop by http://www.seo-guy.com/forum/.