Do you want the convinience of dry yeast or the quality of a properly prepared liquid yeast culture?
Dry yeast is relativly easy to use. Some report great results with just sprinkling it on top of the wort.
A lot like myself properly prepare the dry yeast by rehydrating it as recommended by the manufacturer.
Usually this means sprinkling the yeast into a cup of water at 110f and leave it for 10 to 15 minutes.
Then stirring it to suspend the yeast and slowly feed it wort to get it within 10f of the pitching temperature
of the wort. Pitching it within 30 minutes of rehydrating it.
With liquid yeast it is recommended that you increase the pitching rate by making a starter wort
of aprox. 1 liter of 1040 sg and pitching your activated pack into it. Fermenting the starter at room
temperature for a day or so. This can either be pitched as is for ales due to the relative low volume
of starter wort.
For lagers you really need a gallon starter in order to get the yeast cell volume for a healthy ferment.
You start with a liter and bump it up when the liter one is started fermenting ( you want yeast growth
at this time, not yeast fermentation ) and when it has reached high krausen it is ready. I usually cold crash
my gallon starter to just get the slurrey and discard the spent wort on top of the yeast layer in the starter.
Also for lagers, I pitch slightly colder yeast slurrey into wort that is at fermenting temps of ( for me ) 50f.
This will prevent the formation of esters and higher alcohols ( fusels ) that aren't good in a lager.
You will notice a slower lag start for fermentation doing it my way as the colder fermenting temps
will cause CO2 that would normally be evident in a ale ferment, to be absorbed in the colder wort of the
lager before being saturated with CO2 and then releasing it to the airlock.
Finally different yeasts themselves have different flavour contributations, and you should familarize yourself
with the yeast profiles of the beer you want to ferment.
How do you BBQ an elephant? First you get your elephant....