Go to YouTube and watch the Vid on laying Blocks and Bricks using Mortar Joint Spacers. They make laying masonry Block and Brick EZ, Fast and Foolproof!
Best advice? Home Depot can tell you everything you need to know. You need to be diligent in stringing a good level plumb line. Concrete needs to season, and you surely don't want to crete your blocks in on a wet or humid day. I favor quikcrete for setting in.
You need to first work on the foundation and the base with crushed rock, etc. before ever getting into working with the cement blocks. Make sure the area is level too.
Cement blocks works should be done by a good worker as its contents should be absolutely correct
while mixing water + cement. If its not correct chances are more to break soon. Cement should
be of a brand company and not locals.