I don't think Sejuani is always a good pick here. If you are in low elo I don't think that Sejuani is always a good pick but It's good a lot times. If you play well and for example have a teammate who is good in earlygame it is good to give him feed and help him or you can gank botlane.

You start, with Red and then take Raptors. After this, if you are against a good matchup you go for the Scuttlecrab on the side where you started. If you are against a hard matchup you go for your Wolves and then take that side's Scuttlecrab. Then you take blue and frog, then back. After this, you can go ganking and go for the stuff that is respawning or against a good matchup counterjungle.