Dan,
Different decal manufacturers products will have different effects with Micro-set/Sol, Mr. Mark Softer, Sovlaset etc etc.........Also depends on the clear decal paper type, the type of inks used, the printing process, the clear carrier film.........too many variables to make any hard-and-fast rules.
Always test the decal solvent on a decal that won't be easily seen or missed (in case it ends up ruined) -
I also will often place the decal and then try to allow the setting solution run under the decal - again, with the thicker decals (like some of the Tamiya 1/12 GP bike decals) letting the decal wrinkle up and then lay down by itself doesn't always work..........sometimes I've ended up with permanently wrinkled decals.
Never just buy another kit to get decals - your local hobby shop should be able to order them for you - if they can't be bothered doing this for you, I'd buy my models elsewhere.
Every model manufacturer has a distributor (Marco Polo, for example, imports many different brands into the US) and it's their job to service their clients (both the model shops and the end users).
I've purchased replacements parts and decals many times from our Tamiya distributor here in Oz (they make it harder than it needs to be, though) but it eventually worked.
Cheers
LeeTree