When it comes to using methods, I guess you should pick the one that feels best for you. It also depends on what you want to manifest. If it is money, feel as a rich person, think about what you already have, be grateful for it. When it comes to manifesting relationship, acting as if you already had one would maybe be counterproductive as you pointed out, so you may choose expecting, making preparations like the relationship is on its way(like working out to look more attractive perhaps?
).