Hi! Pinterest and Canva have been a lifeline for me...I bought some plain crates, painted them in my colour scheme and stencilled on wording - a similar thing might work for signs? Happy to help with other ideas if that would be useful? Enjoy the creative side of wedding planning!
I second Kathryn's sentiments! Canva is AMAZING. I do use it for work (I am in Marketing) and thus use the Pro version (which I do actually recommend to pay for if you are designing everything yourself - they can print everything out for you too). It is great for suggesting designs. I used a template on Canva for my wedding invites and then just altered it to the style/colours etc. I liked!
If you already have all of your supplies I would just the Canva templates it for some inspiration!
Congrats on your upcoming wedding! Signs are a nice personal touch. Maybe keep it simple with your monogram/colors in a clean font? Pictures of the venue or homemade decor items could also work. You could even feature favorite things about each other. Don't stress over perfection - your love is the real message. I'm sure whatever you create with care will be wonderful. Wishing you all the best as you plan such a special day!