If you want to rent your first amulet, and have no access to rent directly from a temple (or better still, straight from monk's hand), do not simply pop into any amulet shop and ask for recommendation.
Business is business.
Amulet shop staff or owner will sure push something costly to you, and it could be a fake.
In my humble opinion, the first amulet to get, is Luang Phu Thuad.
Luang Phu Thuad is a very common amulet.
The reason why Luang Phu Thuad is recommended, is Luang Phu Thuad proclaimed that any amulet made using his image, no matter blessed or unblessed, he will protect the owner/wearer.
Guess this reason alone is good enough right ?