alt tags in images question

Can I repeat keywords in different images without penatly or should each image have a unique keyword?

Try and give them unique keywords. I wouldn't use all the same for the sake of Google's over optimization penalty. Even if it's like alt="keyword_1", alt="keyword_2" add some sort of variation to be safe. You can have a few images with the same alt tag but make sure you have a bunch of images without the exact keyword alt tag to keep the frequency down.

you can go with little bit keyword adding words like If you have main keyword "designing" so you can use it like that "web designing" , " page designing" , "creative designing".......