#syn tag

for blending:

try and pick scenes with similar lighting, it usually makes life a lot easier, unless you're doing something like double exposure which requires high contrast etc.

if you're blending two faces (which I do a lot because it's simple and effective, x and x) it's great to use scenes where they're looking at each other because the shadows fall on opposite halves of their faces; it's really easy to use overlapping shadows to create a cohesive whole

building on the above, if a certain blend doesn't seem to be working because the shadows on their faces don't overlap perfectly, play around with the relative sizes of the faces and also how close/far apart they are! in the first set I linked above, their faces are different sizes because it made for a more seamless blend + made it more interesting to look at; for the first gif in the second set, I moved their faces really close together (partly for theme-purposes but also because it made the blend more seamless; this doesn't always work)

if you're not blending two faces, there's a lot of interesting things you can do! like in becca's tutorial above, you can have a closeup of a face and then another gif with more motion/elements that comes through in darker areas, like I did in the first gif here

or you can just blend two scenes with more action in them; in this case, just make sure that each scene has enough light/dark contrast for the other scene to show through when blended. I'm not the best at this, and it does take a lot of trial and error and figuring out which scenes actually work, but the end result is usually worth it (I'm not great at this; I usually cop out and just make both scenes black&white and increase the contrast like the last gif here)

very very important to clean up blends using black paint on an empty layer set to soft light!! I'm pretty sure the tutorials I linked above cover this; also don't be afraid to go in with the eraser sometimes to completely remove pesky parts of a gif (like really bright earrings or lamps) but be careful if you do

for colouring:

most of the time I make life easier for myself by not picking scenes with too much movement lmao; it's really easy to paint around a relatively stationary subject (my go-to is colour fill layer set to colour, the subject erased with a large brush (100-150 px, sometimes 50 px to clean up edges)

play around with modes! sometimes, I set the colour fill layer to vivid and decrease opacity, or soft light/overlay and stack it on top of another layer set to colour

it's really great if a scene has a lot of cyan/blue in the background! you can always make cyan more blue by upping magentas in selective colour (or do the reverse to make blues more cyan), and then carefully use hue/sat to shift the whole thing to some other cool colour (purple and turquoise are easiest, but sometimes you can manage green)

it's a little harder to manipulate red/orange/yellow backgrounds because that often messes up characters' skintones so usually if I have to deal with those scenes I play into those colours by just making them more vibrant and using layer masks to preserve skintones

for sets with multiple accent colours, pick colours of similar vibrancy/darkness/saturation so you don't have to worry too much about cohesion