Sizing with hide glue...

[PatM]

Thanks, Mike. I've really been struggling with my sinewing. It's rough and lumpy and flies off before I can even brace the bow. 

[Stick Bender]

Rather bin there is a couple excelent books on sinew process out there , but one of the best ones that breaks down the sinew process  in the most meticulious format & exsplanation is Adam Korpowitz  turk bow book its geared towards horn bows but its worth its weight in gold for any sinew bow if your interested .

[BowEd]

That's only one reason why hide glue & sinew is such amazing stuff and more than strong enough for any designed bow out there RatherBin.The only draw back is it's not water proof,but multiple thin layered barriers over it make it pretty durable I've found.If that's your preference.Should work fine on your elm bow.
To answer the second half of your question.I use saran wrap over a bow thats' going to set a while after sizing and before sinewing to lessen any contamination,plus a light sanding prior to resizing will help accept the sinew good and proper.
Adams' book is quite detailed about sinewing and I would say the highest standard method out there.