I'd like to add the suggestion to roll ALL coats vertically, top-to-bottom, as that's what's worked best for me. It also makes it less likely to run the roller dry partway through a run because top-to-bottom is less distance than side-to-side on a screen.
I make sure to do all my rolling, loading, edge-cleaning/rolling, etc..in the same direction (up-to-down, far-to-near), as if pretending the roller itself can't even turn the other way. It's easy, and I never really thought much about it until I was going really fast on a screen and rolled back upwards instead of starting from the top again and noticed the roller nap fluffed outward like an animal pet from tail-to-head.
Going both directions didn't seem to murder the screen, but the roller looked like it would be doing terrible things so I've made a more conscious effort to keep doing things the one way.
If you're having troubles with leaving thick-ish roller edge marks behind as you paint, rolling the roller's edges at a slight angle with one end up in the air diagonally and the other on the paint-tray's "washboard" (the angled, bumpy section) to get some of the extra paint off the roller's edges can help a lot.
The build-up of extra paint along the roller's outside edges is the biggest creator of problems for rolling.
I generally load the roller up with paint, give it a roll all-the-way-around on the washboard (using only the roller's weight to push down)just to make sure I'm not dripping, and then give a quick rotation all-the-way-around on the washboard with each end of the roller (tilting the roller diagonal..one end slightly up in the air).
Then roll a row onto the screen/surface.
For the rows, the roller's own weight is all I use for pressure against the surface unless I'm consistently leaving a slight dry patch in the row in which case I'll give a very light pressure as I get to that part.
Load, roll the edges on the washboard, roll a second row with a couple inches overlapping the first.
After you've rolled the second row, instead of reloading and starting a third, skip reloading for now and give a top-to-bottom pass across the two rows you've rolled so far using only the roller's weight, starting halfway off the screen's side and halfway on the first row, and then overlapping each pass by a couple inches with the next until you make it back to the point where you stopped.
Then load the roller, roll the edges on the washboard, roll a third row with a couple inches overlapping the second.
Repeat for a fourth row.
After getting your two new rows, instead of reloading, roll over the two fresh rows starting halfway on the third row and halfway on the older second row..and repeat the top-to-bottom couple inches overlapping gentle passes till you make it to your present stopping point.
Then reload, clean the edges, make a new row, and repeat the two-row process till you've finished the first coat.
The rolling on the screen after ~2rows won't fix really bad roller-marks usually, but it can help smaller imperfections and smaller roller-marks by getting the surface a little more uniform. This is done without loading the roller (right after rolling the second row), it should be fine to overlap your rows during this a couple inches..and I still have just been letting the roller's weight provide all the pressure. Not pushing unless there's a noticeable thin patch that can be subtly filled in during this last pass.
I'd imagine a more experienced roller could skip this step entirely, but it seems to help for me.
Here's a short video showing what the above-mentioned process looks like:
Let the first plain coat (or slightly thinned plain coat) dry at least 2-3hours (the longer, the better) and then repeat the whole thing using your mix (NOT thinned) for a second coat.
Usually two coats is plenty even if you're covering a tricky surface (about a quart per coat on a 110" screen). The lighter-colored mixes when painted onto a light-colored/white surface can often get away with a single coat.
Hopefully this advice will make your first rolling a success.
Using the earlier rolling instructions I would buy a ~$10 gallon of ColorPlace(walmart brand) flat interior paint OR a ~$15 gallon of Glidden Pro/Professional(HomeDepot) flat interior paint and pour about 1quart into a separate container to mix with about 8oz of water and use that for the first coat..let it dry a few hours and then shine a light sideways onto it to check if any areas could use a quick sanding.
This thinned paint will likely run, so protect your floor and the wall wherever it could drip.
Then I would use a quart can of ~$15 Disney/Glidden magnificent metallic "untinted" (from Walmart) OR a quart can of ~$22 RalphLauren silver tintable metallic (from HomeDepot) and have the store shake it up but not add any tint.
Then in a separate container I'd mix the whole can of metallic together with required amount of flat-grey from the gallon container (NOT anything that's been thinned with water)..and use the same rolling instructions to roll a coat using this mix.
Watch the video below the instructions too if possible. I like to make sure the roller has a good amount of paint on it for each row because I use practically no pressure while painting even if the surface is up on a wall. Even while loading the roller with paint I never pressure it into the pan..it's all just letting the roller do the work. ..'cause I'm lazy...and it helps avoid roller-marks and texture.