The trick for me was to take it to my local golf shop. I ordered the grip from the Scotty website and took it in with me. They did it for free.

i usually mark the shaft centre before removing the old grip. then use that mark to line up the new one. then while the solvent is still wet, roll a few putts and see what it feels like. its easy to adjust it slightly before it dries.

Even if it costs you some $, I would suggest to let a professinal do the job
They can also place the grip the way it suits your hands most

As mentioned above, marking the shaft center in relation to your existing grip before you take it off is a great to get it back to where you want it. I do this by first putting a piece of tape (something like the blue or green painters tape works well) on the shaft just below the old grip. Then, using a sharpie or pen, make a line at the center point. Take off the old grip and tape, clean the shaft, put your grip tape on, plenty of grip solvent and then slide on the new grip. Having the line just below the grip for a reference point for alignment will get you very close but you definitely have some time before it dries for tweaking it until it is just where you want it. Once you are happy, set it aside and don't touch it for an hour or 2. Grips are one of the easiest diy jobs when it comes to golf clubs. I enjoy it...hope you do too!

I stopped putting my grips on years ago. I let the professional do it for me. If you go to one shop, purchase your clubs thru them, get fit thru them, I am sure they will work with you. Makes all the difference and saves time.

I do all my own grips due to too many bad experiences with shops doing it for me and I do the same as mentioned above... mark the shaft center, install the grip, double-check and be sure.

Putter grips are expensive and if you don't think you'll be sure, then take it somewhere.

Thanks for the advice. All good tips!