@Michael H.F. Wilkinson
> Authority is obtained through force of personality, prior achievements, and (most importantly!!) through the quality of arguments given, but not through suit and tie.
First, I must apologise - I laughed.
The thing about working outside of academia is that almost NONE of the decision makers one comes across have the background knowledge or time to assess each proposal, suggestion, argument or bright idea on its technical merits (or otherwise). Having your particular views accepted is essentially a sales process, possibly with some internal politics throw in. It's not a detached and objective weighing of benefits, costs, feasibility and risk. The primary assessment is of the person, not the task.
So, given that you are effectively trying to SELL your suggestion better than the proponents of all the alternatives are pitching theirs, what measures are likely (or: historically have been shown to be successful) to help you gain approval from a time-limited, risk averse and technically second-rate decision maker - possibly one whom you rarely have any contact with (presuming the idea you're proposing is big enough)?
Might I suggest that as well as knowing what you're talking about - just like all your competitors do - that the appearance of professionalism and the flattery that you're taking the process seriously would certainly not harm your presentation. If you can achieve that in a scruffy pair of old jeans and a Primark teeshirt then good on you.
To wind up, while I've taken an example of swaying the decision making process of a significant project here, people are judging you all the time at work. Maybe only in small ways and maybe they are people who are aware of your technical prowess. However, it's unlikely that you're the only person of any ability in your team, so what's wrong with boosting your profile by being both technically good AND presentable, both at the same time?