Less is more. Don’t over sell.

o·ver·sell  (vr-sl)

tr.v. o·ver·sold (-sld), o·ver·sell·ing, o·ver·sells

1. To contract to sell more of (a stock or commodity) than can be delivered.
2. To be too eager or insistent in attempting to sell something to.
3. To present with excessive or unwarranted enthusiasm; overpraise.
No I’m not talking about what airlines and hotels do.  They sell more seats and more rooms because they know from experience how many people are likely not to show up.  Rather I’m talking about over selling ideas in a pitch.
Recently we did a pitch and, on my insistence, we clobbered the poor client with all sorts of data which left us little time for what the client had come for.  We gave every detail about the cow that by the time we got to the juicy part, the creative, we had lost some of  the client’s attention.
You don’t have to prove that you know everything about a client’s business to make the sale.  You just need to give the client one compelling reason to buy.
Learn from my misteak (get it?).