theGardener, No worries and hey o/
Making blanks is a terrbile time sink that causes more hassel than not, most often haha. Patience when doing them is the main thing imo. For the extra types which I see your after, I try to write down what I associate with the type, e.g. poison you go with chemicals, skull n' cross bones, etc Then try to translate that into something visual; in this case you'd go with what you have, some sort of greeny, purple, mix. But it'd need that something extra, something that sets the texture apart from the others, like Dragon has recently.
If it helps, I generally open up water type textures, then try every other type (from psychic to colorless) and use photoshop filters first, like color burn etc, to see what it comes out like