Closely aligned to pressing is the whole issue of fusible interfacing.
I am a seasoned enough sewer to remember when these first hit the market in a big way - all those terrible fibre/pelon stiff fusibles that bubbled and ruined many a good garment.
Fortunately things have come a long way since then. I nearly always use fusibles now except for real delicate fabric like silk or silk chiffon (not a large part of my day-to-day wardrobe as you can probably figure out) in which cases I will use a sew-in like silk organza.
Back to fusible.
This is what I use and what I want new sewers to know about fusible interfacings.
Bear in mind that this is sewing according to Babs and maybe not the last word, or even the first one, in some areas.
1. You want your fusible to move and act like your fabric. So woven fabric needs woven interfacing (as opposed to the pylon, fibre type). Knits need knit interfacing (the stuff that looks like slip material). I personally use Fuse a knit types for knits and source all other interfacing (and sometimes my knit fusibles too, from Pamela's Fashion Supply here. IMO opinion no better interfacing anywhere, very professional quality. Trust me on this I. I am actually an old sewer and have used everything that doesn't work out there.
2. The hot glue element of fusing means that the process will add some heft during fusing that you are not going to detect in your hand. Rule of thumb- always use a fusible that is lighter in weight than the fabric you are fusing it to. You don't want your interfacing to change the hand of the fabric, or to overwhelm it. Otherwise you might get this look- collars and details are too stiff and don't lie flat on the body or the garment:
3. Unless you are using an interfacing, like listed above, that do not need to be pre-shrunk, and your fabric is pre-shrunk as it should be, put your interfacing in hot water and hang it to dry. You don't want your interfacing shrinking and pulling in your fabric after the first wash.
4. O.K. now what you really want to know. How do you keep it from bubbling or rippling?
Thing to think about is what is actually working when you fuse.
The glue, either dots or a film, on the fusible side is there to be melted by heat. Once it starts melting it attaches the two fabric layers, your garment fabric and the interfacing together, and when it cools that fuse becomes solid.
The take-away here is, no matter what else you do, once you have the heat (and maybe steam too - check the instructions for your particular product, some too require real pressure again with the products from Fashion Supply) into the fabric/interfacing- don't move anything until you let it all cool down and set.
Moving around your iron, or moving the fabric while it is still warm and setting, you are just building in wrinkles and bubbles. Oh and by the way use a thin pressing cloth to protect your iron. And if you get glue on the iron just let it warm up and scrape it off with a wooden spoon.
5. I do most of my interfacing pressing with the interfacing layer on the underside and the fabric on top. This actually places the glue layer so it is drawn into the fabric by the heat and not just melted over it.