The requested post on travelling will come tomorrow (if all goes well) and Monday (if I get too busy tomorrow) but here's how poison will (probably) work and easily adaptable to your favourite rules as well.
Note that this is meant to make poison a far smaller threat than it is currently. If that is not right for your game, ignore it.
When a character is struck by a poisoned attack or threat, the player should mark 3 Poison Markers on their character sheet.
If you like external trinkets, use small "gems" or pebbles as Poison Tokens and give them to the player.
Monsters of level 5+ will inflict one additional marker per attack.
If a character has ANY poison tokens currently, any additional poison attack adds one single marker.
At the conclusion of each action taken by the character, grab a handful of D20's and roll one Poison saving throw per Poison Token currently on the character.
Each failed save causes 1 token to remain and 1 HP to be lost.
Each passed save causes 1 token to be removed.
Optionally, any Save die scoring a 1 causes 1 additional Poison Token to be added.
A suitable anti-venom for the poison in question will remove 1D6 Poison Tokens upon ingestion.
It is common in games to have anti-venom be generic and work on any poison. More realism-inclined GM's will restrict this.
Medical treatment (requiring a successful skill check) adds a +1 bonus to the next saving throw.
Upon the characters immediate next action, they may attempt to bleed the wound to remove some of the poison (Note that this is probably unrealistic but its a staple in pulp novels).
This inflicts 1 HP of damage automatically but will remove a single Poison Token.
A character reduced to 3 HP or less is incapable of taking any actions if they have any Poison Tokens on their character sheet.
Optionally, heroic characters may move at half speed (crawling) but can take no other actions.