My suggestions/things I learned the hard way:
Mill the grains very fine.
Use a steamer basket to keep the bag off the kettle.
Make a custom shaped bag out of voile deep enough that you can grab the bag and tie it in a knot.
Have a hook, cross bar, or pully system to support the bag over the kettle.
Clip the bag (open) to the edges of the steamer basket.
Use the full volume of water in your mash and forget about sparging.
Heat the water, basket, and bag to strike temp (just slightly over mash temp).
Add the grains while stiring, stir every 15 vto 30 minutes.
Mash at recipe time and temp then raise temp to 170F for 10 min.
Pull the bag and support over the kettle then SCOOB (squeeze crap out of bag).
Toss the grains, keep the bag for re-use.
Take a starting gravity reading.
Boil the wort per recipe.
Take an original gravity reading.
Cool, pitch yeast, ferment, enjoy.
Take carefull notes of water volumes, strike temp, water losses, etc. so you can dial in/adjust next time/calculate brew house efficiency.
I always forget to take the starting gravity.