Did I hear someone whisper my name? Looks like a few have taken care of the answer, but:
I originally started making my lettering flat, but went to the 60 and 90 degree "V" bit, and clean out the letters if necessary. Your picture looks like you wanted a bit of an angle, but wanted a flat bottom letter. When you want flat bit lettering, you can use flute bits. You can get them as small at 1/4 or 1/8" diameter. I can upload a picture of what I've used, if needed. You can use the "V" bit to get a nice angle then clean out the lettering with a flute bit to accomplish the flat bottom.
To be able to keep the router steady, you'll need good, sharp bits. It will be like a hot knife through butter. This is especially important if the grain is real close together, as a dull bit will make it harder to keep straight lines, which is what it looks like happened in your picture.
Also, I don't clamp my wood down. Looking at the second picture, you'll see what I use, which is kitchen drawer liner. I get the thicker kind, which when it gets full of sawdust, I've vacuumed it off, which recharges its' hold, or I've shaken off the big stuff, and did a quick dunk in soapy water, rinsed it, and hung it to dry, and it's like new again. My set up may be in one of my pictures of my shop.
Below are some of my earlier works: All free hand, with a full size router. I eventually went to a compact, because it's easier to lift. I've also used CNC bits to get the effect I'm looking for.
...And on that note, I'll crawl back in my hole. Hope everyone is well.