General House Rules first!
Character Creation and Gear - Specific GMs need changes for their game. These a good starting point.
Ability Scores at 1st level: in addition PCs get 2 extra skill proficiency's
Skill points per level: Extra skill proficiency when they would normally get skill proficiency's
Alignment: True Neutral can be used as Unaligned. For the purposes of alignment related spells or effects Unaligned are considered True Neutral. Most "normal" people are considered Unaligned.
Non LG Paladins: Alternate Paladins, called Templars, are allowed. You don't have to worship a G/LG/LN god to be a paladin. But as a holy warrior for your god you will need to be within one step of your deities alignment.
Starting GP: Starting Money is 150sp. This is for everything above and beyond the Standard Adventurer's Kit. (see notes below).
Ammunition: Unless it's special in some way (i.e. magical +2 arrows) or would be very hard to replace in a given situation (replacing an arrow in the desert) most ammunition is for all intents and purposes unlimited. PC's should "carry" 20 bolts/arrows/bullets for the purposes of weight.
Food/Water: Unless it's special in some way (magical rations) or would be very hard to replace in a given situation (obtaining water in the desert) most food/water is for all intents and purposes unlimited.
Sling: Unless specifically stated otherwise all PC's are considered to have a sling and 20 stones in their gear. (This was learned by every PC during Adventuring 101).
Club: Unless specifically stated otherwise all PC's are considered to have a club in their gear. (This was learned by every PC during Adventuring 101).
Healing
Back from the dead: Raise Dead - per PHB rules, except removing enervated condition.
Combat
You Roll, I Roll: Anytime a healing/cure spell roll has any 1s, the caster can ask for a of the dice with 1s, the DM does re-roll (or allows the player). The re-roll stands.
Movement
Diagonal movement: All diagonal moves are 5'. Get rid of the 5'/10'/5' diagonal move thing.
Other/Misc Stuff?