After purchasing land to build a home on, it usually takes a few months to do surveying, site and soil evaluation for foundation/septic/well (if necessary), and other paperwork.  In those few months, is it a good strategy to advertise the land as a site for a custom home to a potential buyer?  I assume this would entail putting up nice designs and floor plans on the big online real estate sites. Possibly putting up flyers on a post on the property for people driving by to take.  

Or if I already have designs in mind for the land, should I just focus on completing those building plans, estimating costs, acquiring a construction loan, and getting the plans through the permitting process? Basically, what are the advantages and disadvantages of building a spec home that is compatible with the desires of the majority of home buyers vs building a custom home for a specific client?  

I understand that a buyer who wants to build a custom home on the land could take out the construction loan themselves and I would become the General Contractor.  Is this the only way to protect myself in case the buyer backs out and I'm left with a custom home that will be harder to sell? Also, in this case, what happens to the land, which I own?  

Finally, which one can offer the best return on investment while also accounting for risk?       

Thanks for any advice you can offer.