For me, I decarb the bud same as I would for edibles. some like to use coconut oil but I use almond oil because it seems to absorb into the skin better

I make a salve with infused coconut oil, olive oil, bees wax and menthol crystals. I will also infuse the olive oil with scotch bonnet peppers or habaneros (a hot pepper with plenty of capsaicin) and fresh ginger for inflammation. It smells awful but it’s good stuff. Basic proportions below.
63% olive oil
17% beeswax
20% infused coconut oil
1-5% of total oils/wax in fragrance or essential oils (see skin safe usage rates for oil)
Up to 13% menthol crystals

Mix oils (except fragrance or essential oils) and bees wax in heat safe vessel and heat in water bath until melted. Remove from water bath and stir in menthol crystals and fragrance/essential oils. Stir well and pour into container for storage. Use topically for achy/painful muscles and joints.