Bottom line, you do not need to worry too much about not having too much money allocated for the most important and beautiful day of your life, because there have been and there still are many couples in this situation and almost all of them were able to have the wedding they have always wanted, and that because they knew how to spend their money intelligently. You can do that, too, as long as you have a good plan to follow and as long as you have a pretty good idea about how large or small your budget for the wedding is.
Know what colors your wedding is themed around. This should not be a problem for brides but if the groom is taking on the task of ordering the invitations, he should definitely collaborate with the bride or the maid_of_honor to ensure no mistakes are made. It would be a travesty if the wedding colors are pink and mint green and the invitations are ordered as lime green and coral.