You should probably shadow/observe or work in sterilization before you jump into chairside assisting. Chairside assisting involves quite a lot - not just suctioning, but also setting up for each procedure (so you have to know what the next procedure is going to be, and know everything that will be needed for that procedure), passing instruments (so you have to know the order s/he needs instruments in for each procedure), mixing cements (which, for certain kinds of cement, isn't as easy as just mixing the catalyst and base together all willy nilly), retracting tongue and/or cheek, and quite a bit more. I don't think it's a good idea to jump straight into chairside assisting without at the most basic, knowing the names of some of the instruments and when they are used.