Creating grids to aid in manifestation is one of the most exciting ways to use crystals. The best advice I can offer is to not allow the process to overwhelm you. There are no "rules" and you can't do it "wrong".
If you Google "grids", you will find an abundance of opinions as to which works best. Many people use sacred geometry, others use various templates you can easily find online and print off. Personally, I prefer to use my creativity and allow my intuition to guide me.
Finding a romantic partner who is a good fit can be a challenge. A huge part of the process is empowering yourself. One way you can do that is with a crystal grid.
Rose Quartz is the stone of universal love and infinite peace. Rose Quartz has long been associated with romantic love, teaching us the true essence of love and opens our hearts to receiving love.
Amethyst - I always recommend balancing the romantic with the practical. Amethyst is extremely protective and will keep those who (while they may seek a romantic connection) are not in alignment with your highest good.
Clear Quartz is a master healer, amplifying the energies of the crystals around it. It also helps you gain clarity in situations where the path ahead is uncertain. Including clear quartz in your grid, particularly as a centerpiece, is a great way to boost the energy and further focus your intention.
I recommend placing your grid somewhere that the crystals will not be disturbed. If something does happen, don't allow that to stress you. Perhaps you can see this as an opportunity to cleanse and charge the crystals, resetting the grid and restating your intention. It's important (in my experience) to clearly state your intentions. Make a list and read it aloud if you feel that would work best for you. I always close with "Please lead me to the tools I need and the path I need to be on in order to see my goals to fruition."
Pay attention to little nudges from the Universe. Accept those invites to social gatherings. Explore the community and see if there are any clubs, groups, or activities that you are interested in trying. Get yourself out there, do the work needed to manifest your goal, and get ready to embrace the gifts awaiting you.