Doing the Audit
I think the standard process you choose depends largely on the resources available for doing the audit. Bare audit could be something as simple as expert review done by one usability expert. The expert should at minimum base his evaluation at least partially on some heuristics/criteria as there is evidence that this leads to more problems found (Bastien & Scapin, 1995). Regarding heuristics Nielsen's heuristics are a reasonable base as are Shneiderman's Eight Golden Rules. Heuristic evaluation could be more effective if you modify the heuristics to suit the domain.
The thing with heuristic evaluation is to get reliable results you should have several experts doing the evaluating. The best results require the usability experts to be also domain experts. (Nielsen, 1992.) Other problem is that heuristic evaluation does not find actual usability problems, but rather the evaluator infers the problems from various qualities of the UI, which can lead to false alarms. Usability testing works the other way around where UIs problematic features are inferred from the problems users are having.
Generally more expensive way to audit UI would be to do usability testing with representative users. I haven't done too much usability testing, but not counting the cost it seems to me to be the method with least problems and most reliable results. If various stakeholders can be brought to observe the testing it can also be easier way to convince them that changes are needed.
I would in general go with usability testing augmented with as many experts doing the heuristic evaluation as possible. Or even non-experts doing the evaluation as many novices can trump one expert.
Regarding the Recommendations
In essence writing recommendations is all about making them as usable as possible. Bad report isn't useful.
Dumas et al.(2004) recommend that when writing recommendations, you should:
- Emphasize the positive.
- Express your annoyance tactfully.
- Avoid usability jargon.
- Be as specific as you can.
I would add to those that remember to include concrete improvement suggestions with the recommendations. Just pointing out the problem isn't that helpful.