Before I get into this, I'm just gonna let you know that I'm generally a pretty lazy animator so I try to basically always do the minimal amount of frames/layers that I possibly can and I'm also not down with the cool kids and their tweening/onion skinning animations. So yeah, let's get to it aye! Since I'm basic af when it comes to this hopefully it's easy for you to understand too
Ok, so using that same pic for ex., basically what I do is after I create the main piece and move on to the animations, I make a separate folder for my blinking frames/layers.
Then, I make a separate layer for my sparkling/twinkling and I just adjust the opacity per frame (this way I don't have to clog up my frames/layers w/making all these separate twinkles)
e.g. the layers I used for this piece
when I do regular blinking animations I usually keep it to a minimum of 4 layers, 'h' stands for half and 'c' stands for closed, those are just my ways of easily identifying my layers. 'h2' is just a copy layer of 'h'. And the sparkle layer is for the sparkle.
This DP had 12 frames total, the first frame is just the blank non-animated frame (just the base frame)
[ time set to 1 second ]
The next 8 frames are the sparkling frames where I gradually adjusted the opacity of the 'sparkle' layer. (basically went 15% > 25% > 50% > 75% > 100% > 65% > 35% > 10%, I don't always follow this, but it's just to give you a rough idea of how I scale up/down with the sparkle)
[ time set for all of these = 0 seconds/no delay, except for the layer with 100% opacity which is set to .1 second )
After that I move on to the blinking frames, which is pretty self-explanatory
[ time for these .1 second ]
and I set the animation repeater to "Forever" :^ )
then save for web and donezo, lmk if you need clarification on anything!