Any tips on how best to utilise infantry?

I'm finding that there's almost no point of bringing them, unless you're running 120 Guardsmen and intend on swarming objectives.

My usual game goes: 2 x 20 man Catachan squads both Scout 6" move up on the flanks; both squads are usually dead by my opponent's turn 2 (if they go first).

If I go first it usually isn't that bad to be fair. Is it worth staying back and in cover if my opponent gets first turn? Or perhaps moving the squad so they're most likely going to stay out of line of sight?

I've considered maybe keeping a squad of 20 Catachans in reserves but then they wouldn't get to utilise their Scouts move at all.

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