I use a duo fiber / dab brush, specifically the Elf Small Stippling Brush. I’ve tried others and all of them work, but the elven brush seems to be a bit denser and fits easily into any component. This method can take a little longer, but the end result is well worth the effort. I get a better mix and have more control over the pigmentation, which is especially important when it comes to deeper shades.
With creams, I just dip straight into the brush and then blend into my face. For liquids, I usually apply to a palette and then pick it up with my brush, although sometimes I dab on with my fingers and then mix with the brush. If necessary, I press the product into my skin with the warmth of my fingers / hands.