I also like to use this website for reference.
Counting waves is hard. I screw it up all the time. Not to mention, waves sequences can "morph" themselves depending on momentum (a clear Wave 3 can be come a wave 1 if the momentum is high). I found that using support and resistance trend lines makes wave counting easier. For uptrends, connecting the lows gives you a reference line to id corrective waves as they will break the line to the down side. Resistance trendlines are used for downtrends to id when the market shift to a new uptrend.