The 3d printing toobox is pretty good already. Enable it in your user preferences.
Now, as an owner of an FDM 3d printer (Solidoodle 3), I believe I am in a unique position to give you more details on the steps it takes to prepair a model for 3d printing. Either on a home unit, or through services such as Shapeways.
First, you want look at your model as if it were a vase, and you need it to hold water. There should be no holes in the surface that would let the water out. This is called manifold, and its important for how the slicing program processes the .STL file. you want to try to avoid mesh intersections as much as possible as well, but depending on the slicer, they might not be as large an issue.
Next, you need to know what sort of machine you will be printing on. fused deposition method, or one of the powder/resin machines at a service such as Shapeways. for FDM, the design of your model makes all the difference in the world, since overhangs lead to the need for support material, which leads to lots of cleanup if your not using an expensive unit with fancy water soluable support material. powder machines don’t have this limitation for the most part, and can print very intricate designs without any extra support.
Depending on your choice of machine, you may need to “cut” your model up into printable sections with pins built in to allow you to glue it back together after printing. i have successfully printed very ornately detailed character figures on my printer using this method.
as for modifiers on your model, you will want to apply them all, perhaps turn up sub Ds to get a smooth surface etc (printer doesn’t care how many polygons, although it will take the slicer longer to generate the path file for the machine.) i would suggest saving your model blend to a different name before doing this, as an applied high level of subdivision, will make future editing impossible.
Let me know what sort of machine you are printing on, and post a picture of the object your trying to print, and i can give a few more pointers.