Use comfortable bags and straps.

Equipment instantly feels 50% lighter and 100% more comfortable when using a PRO STRAP.
And there is less risk that your equipment slips off your shoulder, because it does not easely slip over you shoulder.
They are not only available for you camera, but also to replace the existing strap on your bag!
You’ll definitely feel the difference in comfort!

There are many choices from Op/Tech

I use both of these straps:

The Op/Tech Pro Strap:

The Op/Tech Bag Strap:

I use a Lowepro Bag "Stealth Reporter 300AW"
I really like these bags!
They're quick to access and feel very comfortable on the hip.

Description of the Stealth Reporter 300AW

Need extra room?
The Pro AW Side Pocket straps to many Lowepro packs to give you space for other stuff.

(Size (interior): 14.5W x 4.5D x 16.5H cm)

In Holland, they are sold by Foto Konijnenberg

Most of the time, my bag contains the following items:
- Canon 300D Body (Wasia E3kr111B71 firmware) with Op/Tech Pro Strap
- Canon EF 50mm f/1.4 USM
- Canon EF 24-70mm f/2.8L USM
- B&W Slim Circular Polarisation Filter MRC 77mm
- Battery Grip BG-E1
- Canon Speedlite 580 EX Flash
- Lumiquest ProMax system art. LQ-931D
- Camera Plate, Kirk PZ-84 for Canon Digital Rebel with BG-E1
- 1x Canon Accu BP-511 Li-ion 7.4V/1100mAh
- 4x GP Accu BP-511 Li-ion 7.4V/1300mAh
- Canon Battery Charger CB-5L
- 12x LENMAR 1.2V 2500mAh NoMEM NiMH AA Battery for Canon 580 EX flash
- 2x 512MB + 6x 1GB CF Card + 1x 1GB Microdrive (8GB, ~2400 pictures)
- Apacer MEGA Steno Card reader USB2 (Uses same USB-cord as used on the 300D)
- Air Bulp "King" (not for the sensor!)
- Lens cleaning microfiber cloths (dry!)

Then it weights 5.2 kg.