Welcome back.
You probably already read some of the top rated storygames, but consider rereading your favourite and really looking at how it is written. Can give you an idea of what some authors do to make good storygames.
I'd also suggest starting small, writing a storygame ends up being a lot more work than you might expect at first, and trying to write an epic ends in a giving up too often (due to a lack of motivation to finish). With that said, you can still start big, just know it isn't gonna be finished in a few days (if you want it to end up good anyway).
Also, regarding having it end up good, remember to proof read at the end. It helps bring the quality up soooo much, even if it isn't that fun to do.
If you use any sort of variable manipulation / scripting read through the thing checking it all works as intended.
There is a lot more I could probably try to say regarding 'tips on writing', but I feel this should be enough from me, others can probs offer more advice.
Btw you can get more specific writing related feedback in the 'Writing Workshop' forum, might be worth stopping by there early (with a few pages I'd say) to get useful advice on writing, stopping by early means you won't have to go back and change a whole lot of things if there ends up being some consistent mistake in your writing.
Good luck with the writing, and good luck with creating a forum presence.
TL;DR
Proofread at the end, I think starting small is good, get detailed feedback in 'Writing Workshop' forum.
P.S.
Oh also having proper spelling, grammar, pacing and what not all also helps heaps, pretty much anything regarding writing a normal story can translate in some way to storygames (but certain things are more difficult to achieve due to branching, proofreading can help fix a lot at the end when you can see how it all fits together).
