Number one.............start with a full and thorough set of construction design documents. You can get by with what is called permit set which varies from locale to locale, but for the most part a permit set contains the just enough information and the basic requirements of the building department (i.e. plot plan, floor plan, general indications of electrical, mechanical, plumbing, elevations, a typical wall section showing foundation up to and including the roof, and electrical riser and maybe a plumbing riser diagrams)................in other words just the basic information to build your house, which will result in a many allowances for elements that have been decided on. If you're bidding these plans out, invariably the allowances will be for elements on the low end of the quality scale. Upgrades will results in change orders.

Spend the money up front and get a full set of construction documents with specifications as to finishes desired and quality of workmanship expected. Here's what my typical set of house plans includes:

Plot plan - showing the boundary and meets of the property, set backs, utilities (existing and proposed), if it's a complex site (heavily sloped, obvious drainage issues, streams, ponds, etc., etc.) I'll have it surveyed to include the contours on the plan. The proposed footprint is tied to a property corner and all the proposed hardscape and softscape elements are indicated. Optional would be a landscape plan done by an associate landscape designer.

Foundation / basement plan - typical details
Floor framing or slab plan - typical details
Floor plan - dimensional and wall types - typical details
Floor notation plan - notes, detail call outs, interior elevations, cabinet elevations
Roof layout plan - (framing plan or truss layout plan) - typical details
Electrical plan - typical details - riser -fixture schedule
Mechanical plan - typical details - equipment schedule
Plumbing plan - typical details - plumbing riser - fixture schedule
Schedules - finishes, door and window sizes and elevations, details
Building sections - cross and longitudinal
Specialty Details
Specifications

Everything is called out with specifics - finishes, materials, equipment, paint colors, trim, etc., etc......
This way when the client is putting it out for bids, every contractor is bidding on the same thing, if there is an allowance called out it is based on what the client expects not what the builder wants to supply.

Yes, it's more expensive than your typical builder set or permit set to produce (12-15% of the estimated cost of construction), but then most of my project were in the high 6 figures or over cost range..........and most of my clients also hired me to provide CA (construction administration) services as well.

A typical duration for programming, conceptual design, design development and construction documents might be anywhere from 6 - 18 months (the longest) from start to bidding.

The benefits were that the client knew exactly what they were getting, construction progressed in an orderly and efficient manner, conflicts and misunderstandings were minimal, change orders were kept to a minimal rate, and 99% of the time budgets were met.

Now I'm not saying that you need to go to this extent, but the more information that is provided to the contractors, the less guessing, assumptions and misunderstandings you'll experience on the job. That usually results in efficient schedules during construction (time is money), less change orders and better quality in both materials and construction.