Grounding screws are GREEN, too be recognized, as such.
I, always, whether solid, stranded, or a combination, twist the conductors together, PRIOR TO, installing a wire nut.
Unless the connector's manufacturer requires twisting, twisting is optional and is debated to no end. I do it with 3 or more solid and not with stranded. But what do I know? (47+ years master & former inspector)
<To be honest, I like push-ins and Buchanan's instead of twist-ons. They're faster to be sure.>
If you like to pre-twist, here's a hint:
Twist with your linesman (linespeople?) pliers and slightly ease up on the pressure as you slide the jaws toward the end of the conductors. You'll have a nice taper. Then, snip the end at a 45-degree angle. The nut will go on super easy and securely.
Don't pre-twist the fine strand fixture wire into the bundle.
Lay it next to the others that you twisted or didn't twist. Leave it sticking past about 3/16". It'll get wrapped around and pressed tightly (by the spring in the connector) into the others- twisted or not.
Always look at solid wire near the insulation to be sure you didn't nick it with the strippers. It'll break off when you twist- Or worse: Later
When the nut is on, pull each conductor individually.
Don't use the Wire Nut type connectors that don't have a wire spring inside. Some that come with import light fixtures are plain plastic. The wire spring in a real one is square edged and makes a lot of difference. (Those plastic ones make great caps for opened caulking tubes.)
Tool Suggestion:
If you do a lot of twist-on connectors, there are screwdrivers with a socket in the butt of the handle that is used to grip & twist the connector. They work great on hard shell connectors, but don't work too well with the soft sided Wire Nut brand twist-ons. I use the stubby ones with the screw driver end made to slide over conduit fitting set screws. It makes working at odd angles easier. (Klein & Greenlee make them.)
Paul
PS:
Three is only one place in the NEC where the equipment grounding screw has to be green. If I remember correctly, the citation is NFPA 70 at 250.126
That one place is on a wiring device. Examples are a light switch or receptacle outlet. This is the screw that comes installed by the manufacturer. The screw on such devices also has to be not easily removable.
Anywhere else, a grounding screw can be any color your heart desires- even the load center bonding screw (which are green to meet UL, ETL, etc. Not to meet NFPA 70).
The screw can be hex, pan, round, fillister, socket, truss, elevator & more. It's your choice.
