The first thing you should consider is what type of shower you would like this to be. Do you want it to be just for the bride, or for the groom as well? If it is only for the bride, you will only invite her female friends and relatives, while if it is for both then you would invite both genders. Once you have decided this, you are ready to decide who deserves to be invited.
When throwing a shower for another person, it can be difficult to determine who deserves to be invited. The first thing you can do is create your own list of people you think the bride and groom would want at the shower. Once you have created that list, run it by two or three of her close friends or relatives to make sure that you havn’t missed anyone.
Once you have done that, it may be wise to show the final list to the bride. That way, she will be the one making the final decision as far as who is in and who is out.
Determining how many people to invite to the shower all depends on the budget you have set. Try and figure out how much the shower would cost per person and then invite accordingly.