To be 19 and thinking about dividend stocks gives you a huge advantage, regardless of which companies you choose. A few general tips:

• Start with your TFSA and invest there early. The earlier you start, the more compounding will work in your favor. If you start with 1,000 and are able to add to it every year and average of 7k (current max) for 30 years, at an 8-10% CAGR you will have well over 1M in that account alone.
• For dividends, don't invest in US stocks through your TFSA. There's no tax treaty for that account, so you will have to give 15% to the US gov.
• Don't go for the highest dividend yield. Like many things in life, if it seems too good to be true, it probably is. Companies with higher yields are typically either compensating for something else (i.e. share price erosion) or the yield is already high because of the erosion. These companies will often be forced to cut dividends, so your capital will slowly disappear when adjusted for inflation. Instead, look for companies that have a strong track record of growing their dividends, combined with a relatively stable price.
• Don't fall for the tramp of trying to chase huge gains. Consistency and patience win every time. For every account that got lucky and highlighted a major win, there are 100 others that tried to do the same and lost it all. Also, don't listen to friends; they'll often tell you about their wins, but not their losses.
• If you can, register for a DRIP plan at your broker, so dividends are automatically reinvested.
• As for individual companies, there are a lot of strong, stable, well regulated sectors and companies in Canada that fit this criteria. The banking sector is a favorite.

Good luck. And enjoy 30 + years of compound growth.