I am using guides as a grid system to align objects to. Its difficult however to align things I use shapes, find the centre and then make another guide to find the centre. I could potentially make a more complex modular grid system but am just wondering if there is a work around or better more efficient method in doing this?
It looks like you are doing some page layout- Adobe Indesign is made for this. This can certainly be done in Illustrator also with a bit more "hand work".
Your guides can give you some page layout and alignment assistance. I am not sure what you are exactly doing with your guides but perhaps using more of a grid would assist you. And turning on snap to grid (View> Snap to Grid).
It seems like what you would like to master is the Alignment Panel (Window> Align). You can align one or many things to each other, align one or many things to the Artboard, and you can align one or many things to a "Key Object".
Make a selection of 2 or more objects then click a second time on the object which you want the others to be aligned to. This will become the Key Object and have a heavier selection highlight. The Align Panel will then align all other selected objects to this Key Object.
If you have the Control Bar showing at the top of your workspace (Window> Control) then when objects are selected the Align options will be shown there also.