Turn up clean, on time and with the right money, and you won't go far wrong. I find I generally get better service now from the more MILFY type of SP in their 30s and 40s. On some occasions when I've seen an SP in her 20s, I've worried that she's thinking, "Christ, this old git's as old as my dad!" And the service has been rather lacklustre.
As it happens, the other day I was on a reconnaissance mission outside a new parlour that I'm planning on visiting. (Looks good - fairly discreet, safe area, good parking etc.) Whilst I was sat in the car outside, I watched a procession of fat, bald, middle aged old gits surreptitiously scuttle in and out of the front door. It suddenly hit me - fuck! Is that me? (Unfortunately, it is). I think it goes to show that fat, bald, hairy middle-aged gits are an SP's bread and butter, and you're probably no worse than the last punter that she's seen.