As you asked the question i'm assuming you're not into car cleaning and have no products so i'm going to advise you based on cheap stuff for a quick fix before a sale.
The rubber and plastic trims, use some petrol/white spirit on a rag and wipe over it in one smooth motion. Brings them up like new. It will need protecting to make it last, but you're selling it so don't bother.
The rear drums need a good going over with a wire brush and some black hammerite to look nice and fresh.
And for the tar, I'd use Tar and glue remover. (Can get some from halfords)