if you are interested in designing the components inside the Abaqus environment I would suggest that you first create the CAD models in a software like CATIA, Solidworks or Inventor. Since you are dealing with a mechanism it would be extremely helpful if you design the parts/assembly in a CAD software and then decide which features you will use/import in Abaqus/CAE. By that I mean that for a tube you might need to use beam or truss elements (to both simplify the geometry and reduce the computational cost).
Unfortunately, there is no standard way to design geometries and create FE models. When you have a complex system you have to decide which components are crucial for the analysis and need more details and which can be simplified or even omitted.