Braided line is right. A braid of some 0,15-0,22 mm. will do well for most anglers. Besides producing effortless casts, it’ll ensure a nice constant contact to your lure in the waves. You might want to avoid buying the cheap braided lines on the market. The line will take a lot of casts and a lot of beatings in the salt – and you’ll want the line to endure landing a nice big sea trout among the rocks and weeds.