>>30710412google is shit for twitter images. use saucenao ascii2d or tineye.
>>30710531all 3 are just about equally reliable. they all sometimes fail to find the image. if all fail, do an MD5 search and see if someone in the archive has posted the sauce when another asked for it
usually I go to iqdb first because the button is there in 4chanx, then I use the links in picrel to branch out if iqdb can't find anything in the boorus