If it's your first EICR, the best advice I could give is to take LOADS of pictures.
Close ups of anything to be reported but also general pictures of each room and a good few of the DB and supply equipment are always useful. Plenty of times I've been saved a revisit just to check what size/BS number the supply fuse was or some such thing.
A lot of these easy to miss items get picked up if you do the whole report on site straight on to the form/laptop but personally I like to get the essentials on to electraform on site and write observations and stuff at home so I can take my time and check it all through. Having plenty of pictures to scroll through is really helpful if you do it this way. There have also been a couple of times I've spotted an issue on the pictures that I didn't see on site.
Personally I just charge my usual hourly/daily rate for me and a skilled labourer to do the inspection, allowing for an extra hour to prepare the paperwork. I do minimum half day for a small flat and generally a full day for a house with more than one bedroom.
There are definitely cheaper options out there but if you actually want to do a full thorough EICR in an old house with a bunch of dodgy alterations I don't see that you can do it properly in less time.
My clients usually want me to do the best for safety and don't mind paying what that's worth. Clients that don't want to pay for a proper inspection are generally best avoided anyway in my experience.