Economically the signs are positive so by the time the election comes around there should be a good story to tell there.
They need to tackle 'illegal' immigration by investing in processing and deportation centres and not focus on boats and apeing Reform. You aren't stopping at source so stop banging on about smashing gangs and process people quickly once they are here. Make the story about the number that have been sent away, if that's the appropriate response, not the number that have come and not in a dog whistling Rwanda kind of way.
Enact policies you believe in and stick to them, irrespective of what social media or the right wing press says, you aren't winning those battles, don't bother trying.
Most of all ditch Starmer, have a wide pot of candidates to replace him and elect the one that is best able to engage with a positive message. Hopefully that's someone who at the moment is a bit off the radar.