Maybe obvious for some...
Take a material refiner with you when hunting mobs that drop hide and wool, saves a lot of weight on those 100k ped ammo runs.
Depending on how you set up the options in game, I use the right click, move to target when I think I'm barely in range of a mob. If im not close enough to fire, the right click moves your avatar into range and fires auto magically.
On slow boring days, I'll hit the mob with every type of weapon I have, sometimes you get the skill bonus for all of them- blp, laser, melee etc.
Finish off a mob with a lower damage, lower ammo weapon so you not wasting decay by shooting a strikehammer when the mob has 10 HP left. Saves ammo and decay.
If you tp into a hostile area with big mobs and your close to the water, drag them in and they drown.
Using a lower healing fap (like a 5) after a fight buys you a few more chances to bump up that medcial skill.
Killing Marco with a potent firestorm chip will result in a skill requirement nerf - really!
Playing in a high resolution mode, be careful dragging windows to the right side. The fix icon button when you switch to lower resolution doesnt work with loot windows or inventory window.
Disable all the highend graphics when hunting hogglos so you can read the text in the chat window.
Pressing the mouse wheel button will reverse your view in 3rd person angle.
To preserve the life of your very worn gold card, loosen all four screws on the reader and leave the card in it. When you need a number, you just have to press the two pieces together- this stops the contacts from scraping holes in the contacts of the card.
Letting a friend play with the GC reader is a bad idea, if they generate more then 3 numbers without using them, your locked and have to file support case.
When logging off, let the countdown timer expire or you may end up where you were 15 minutes ago. Especially after a tp or a ride to CP/CND.
When using auto run, do NOT answer pm's or you will get stuck in run mode, fixable by selecting lay down but frustrating.
When using the famous cK fap 69, use control click to select multiple party member to heal them all at once.
Hope that helps!
Cheers