Kit vendors use EC-1118 because it's a non-fussy workhorse that has the best likelihood of producing a good result for a beginner with no experienced help. You can get good results by using a different yeast, saving the EC-1118 for problem ferments. I'm not sold on mixing yeasts, as it appears that one is more likely to dominate the other. A common strategy in commercial winemaking is to ferment different batches with different yeasts, and blend post-fermentation.
Before using a yeast, read the description. As
@Khristyjeff noted, if it needs nutrient, add it. I don't recommend waiting until you smell rotten eggs -- H2S is NOT something to play with.
I've been using the FWK protocol since last summer -- When preparing the must, determine the amount of nutrient needed and add 2/3 of it.
Make an overnight starter with 1 cup warm water (90-95 F), 1 packet of yeast, 1 tsp nutrient, and 1 tsp sugar. Put in a sanitized wine bottle and swirl to mix. I leave it on the counter for 4 to 6 hours, then put it with the must overnight, so the temperature acclimates to the fermentation area. In the morning, swirl the starter and gently pour down the side of the fermenter so it doesn't spread. Don't stir for 24 hours.
48 hours after inoculating, add the remaining 1/3 nutrient. There are numerous timings for adding nutrient -- this one works well so I recommend it.