MIG welder settings

I've had a POWER IMIG 250P for several years and have fumbled through a couple of spools of wire but proper settings have me confused. In trying to figure out what I should be starting with checked several different manufacturers charts and as an example, for 0.035 ER70S-6, 75:25 mix on 1/4" steel the recommended settings from three different manufacturers are 19/320, 20/250 and 23/305. Given that, are there rules of thumb one can use? I do understand that getting better requires experience but having a reasonable place to start seems like a good idea.

On a side note, is there a way to retrofit the welder for a spoolgun? Everlast says no but there are some pretty inventive people on the forum.

My 250p has a spoolgun connection. As for settings it's the same for any mig. Set voltage for the metal thickness, start with the wire speed too high and turn it down while running a bead until it welds like you want. I leave my arc force around 7.
The digital readout for wire speed does not represent the actual wire speed. It's just a reference number for repeatable setup. The readout switches to actual welding amps while welding. I like spray arc for 1/4" steel and thicker and use the regular 75/25 gas.
Welds need to be horizontal since it's such a hot process. You can try it by setting your machine to 28v 300 on the wire speed. Keep reducing the volts by .5 and slowing the wire speed a little until you find the lowest setting to keep it in spray. You'll have to experiment with settings for different thickness steel and always use a tapered contact tip to avoid overheating your gun. The arc will be way more quiet than short circuit with no spatter at all. When you find a good setting for whatever, make a note of your settings.

https://www.everlastgenerators.com/f...id=13690&stc=1
You can spray thinner steel also with more argon in the mix. I mixed my 75/25 and pure argon tanks with a tee connector to spray this 11ga square tube. Just keep testing and taking notes.