The process for Cannabis is slightly different from this, so use you google fu to get details. I am nervous to describe it exactly, since I am not truly anonymous here.
For dried plant products, I prefer to use a percolation cone, but that method is not practical for most. It is interesting, though, and faster, so if you are interested in tincturing your own herbs, you may want to google "tincture by percolation."
The most important part of tincturing is knowing the herb weight to mentruum (solvent) volume ratio. I use ounces, since that is what the old docs used and the ratios are eaier to find. At this point, I have my own DB of these values now. You also need to know the kinds of constituents in the plants so you can decide what percent of your menstruum will be alcohol. For the most resinous plants, like Cannabis, you need 95% ethyl alcohol (everclear) at a 1:2 weight to volume ratio.
The process we will us here is called maceration. It basically means soaking. For the most pain relieving Cannabis tincture, I take half of the raw material and spread it out on a cookie sheet, then put it in the oven at its lowest setting for up to 20 minutes. Leave the oven door open about three or four inches. This converts some of the THC into CBD. Chemists have a name for what happens here, I call it magic. After your time is up, or when you get nervous about the smell, take it out and mix it with the half you did not heat. For the headiest, but less anti inflammatory brew, skip that part.
For example, if you have 6 ounces of your herb, put it in a mason jar and pour 12 ounces of everclear over it. Cover and put in a dark place. A kitchen cabinet works nicely. Take it out and shake well every day for at least two weeks, six is better. After this, lay some cheesecloth over a strainer and pour the jar through this, into another jar. Wrap up the cheesecloth and wring as much out of it as you can. It is HARD, but these few ounces are the strongest. You will, under no circumstances, be able to get all 12 oz back. By this method, you will be very lucky to get 9 or 10. This is why I prefer percolation. Pro herbalists use a hydraulic press instead of wringing, but still only get 10 1/2 oz or so. When your arms get tired, run it into ANOTHER jar through a coffee filter. This is the finished product.
Dose varies by individual. Chronic use or tolerance to smoke seems to have no bearing on dosing. Start at about ten drops. Most folks I know wind up between 20 and 40 drops, some need more. It can take several hours to take effect.
Trim works just fine for GREAT product and is tremendously cheaper. Extraction can concentrate chemicals used as fertilizers and sprays to toxic levels, so know your source!