These are my top tips for new players starting Postal.

1. Press F1 when you finish a level to take you to the next one

2. Before pressing F1 pick up health, armour and ammo as you can take it to the next level

3. Set change weapon controls. Using the default brackets is difficult in battle

4. If you are on fire try running into the enemy and they will be too

5. Keep an eye out for gaps or hidden areas. These will likely hide a good stash

6. Don't move too close your enemy has greater chance to hit you up close.

7. Shoot the enemy that's the biggest threat. Most enemies are disrupted by you shooting them so they can't shoot back.

8. Use duck if a missile is heading towards you and can't dodge.

9. Use your rockets on turrets. They will normally die in one shot.

10. Blowing up barrels can be slow with machine gun. Use something a bit more powerful to trigger it

Bonus I should also mention that I did have a bug where my cursor randomly disappeared at the start of the Shopping level. Took me a little time to figure out what happened and get into the menu to bring it back.