Which finite elements are best for structural analysis in engineering courses?

[Dell]

i am a 3rd year engineering student currently a course in computer methods for structural analysis, as a part of the course we are learning about finite elemnts, we have learned about CST LST Q4 and Q8, but i am having difficulty deciding which element to use for different models.
does anyone know of a site or something that has the characteristics and uses for each of these elements, maybe even with some examples?

 

[afreiden]

Triangles and tets are, in general, not advisable due to "shear locking."
You can always use quads, even if you're mesh is highly nonuniform.

Feel free to provide more personal background, the objective of the course you're taking, what (if any) commercial FEA software you are using, etc., and I can perhaps give more detailed answers.