I'm going to play tomorrow too, it's going to be my first pre release, but have played MTG since my teens.
I've done some research and reading online for tips and come to the conclusion that all i can plan for is to simply have fun. There's simply too much variables to assure winning
However here are some tips, i've found that can maybe help us out:
1 - learn the basic rules of the format;
2 - study the set, it's cards and new mechanics;
3 - build you deck with an strategy in mind and don't mix stuff up too much, focus on one strategy and keep in mind that it's a fast format, so try to add a lot of lower costing spells and fewer higher;
4 - When building your deck look to build around rares and mythic rares you'll get on the boosters, because they normally are stronger then commons and uncommons, but also watch out for the 2 recommendation i made, there's some commons and uncommons in this set that are great.
Overall i recommend you to try and have fun and good luck tomorrow, may The One Ring be with you!