First off Welcome to the site ! Always nice to see another Albertan , which part or you in ?
I'm not much into the armor myself , but I will try and be some what of help . Never be disappointed with your efforts . After all it is your first model !!! Yes some guys will do all of the assembly first while others will paint and build in steps . This is neither wrong or right just that builders method which works for them . Even some of us aircraft modellers do it that way as well . In your case maybe just start with painting the parts and then do your assembly as you go until you gain some experience building up your skills . When you feel that things are going well with the results , then move up a step and try something different .
If you don't like it strip the paint of and start again .
You didn't say on whether you use an airbrush or just paint with a brush . What type of paints are you using , Acrylic .......Enamel ?
Decals are funny some times but are easy to use . You first need a gloss surface on the model first . Such as testors gloss coat or future floor wax . You will find that many modellers use future floor wax . This can be airbrushed right for the bottle or you can thin it down with rubbing alcohol or any acrylic thinner will do . Works very well with a brush which is how I do it . Applying a few thin coats . Between each coat wait for 10 to 15 minutes until the next one goes on . Let this fully dry for 24 hours , the same with testors gloss coat .
The goal is to have a glass surface for the decals to adhere to . The specks that are under the decal is silvering , air trap under the decal . This is caused by not having a glossy enough surface . You can get two products that will help the decals stick down better as well ( micro set ) Applied to the area where the decal goes , then the decal on top . The next one is call super sol , very strong stuff . After the decal has dry for 30 minutes brush on a thin coat . This helps the decal into corners or panel lines . Don't worry about it wrinkling on the surface it's just doing it's thing and will level out . Wait for that to dry and if it still needs more apply a little more . When every thing is dried wash off any residue and apply the dull coat .
Seeing the builds can be over whelming , but don't let this get you down . There are lots of talented and helpful people on the site who are more then willing to give aid . From the beginner to the advance . You are armed with the best tool on the bench , asking questions !
we all started some where .
Happy modelling and have fun !