Firstly make sure your Step Ladder is well set up on a firm base (not sand or soft ground) that is not likely to allow any slipping, especially so in the case of rubber base pads on a wet concrete floor. Make sure the spreaders are FULLY locked in place, and stand on the bottom tread to check overall stability.
Remember to face your Step Ladder at right angles to the work, so if painting a wall for example you would be facing the wall, not working to the side.
The most important rule of using a Step Ladder is: NEVER stand on the top tread, however tempting that may be in order to perhaps finish off a job. Step Ladders are labelled with warnings to this effect, and they are there for a reason!
When moving a Step Ladder along to a new working place, pick it up rather than dragging or pushing it along, as this will weaken the joints and make it less stable over time.
When work is finished, clean and store your Step Ladder in a secure place to avoid damage.