For moving objects, there are a few tricks. Here we are talking about moving onjects towars yourlsef.
* Use Tv to control the shutter speed. You will need at least 1/30s (walking person) to 1/8,000s (fast approaching vehicle). You may consider also full manual. (In my case, I often use the P mode and set the shutter speed with the dial.)
* Use Hi Continuous shooting.Do make sure that you switched off (kill off) all in-camera post-processing. (PP)
* Then there are two 'schools'
- AF.C (or Continuous/servo AF)
or
- Manual focus pre-focused to a zone.
I prefer to use the latter because I learned to estimate distances: I set the distance on the focus ring and I start shooting before the object move in that location. I found that this technique gives me the better 'keeper rate'.
(EDIT: catch-in-focus may work for runners and cyclists, but definitely not for motorised objects... or birds.)
Hope that the comments will help.