OT: button image for user tips

I'm having a difficult time of this. It seems like such a simple thing, but it actually isn't. Up until now, have needed only a couple of buttons to give users tips with. Since there is no tooltip functionality yet in FMP, this is my workaround. I've been using a button with a question mark on it in the past, but I'm really not happy with that anymore. I need to add some more buttons now with popup tips and this no longer is good enough.

I know I've seen a "tips" type of button like this in some programs that didn't have text which is where the idea has come from, but can't remember what the icon looked like. I know that the icon image was very clear so that user had no doubt what s/he was clicking on. Not so with the question mark. That could mean anything.

Can anyone help, pls? This is quite important. Hopefully, if not too much trouble, an example graphic file can be attached (?). I'd really appreciate it.

When I find a good icon image, that will be my standard one for user tips for all solutions I create.

Thanks!