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My advice is to optimize the position of your left THUMB. It´s so important. You need the presure at the right spot. Also watch Tonys indexfinger and try to position your indexfinger simular to his. Let the strings ring one after the other and optimize the ankle of the indexfinger and how far it reaches over the second string and the position of the thumb until all strings ring clearly one after the other.
Last not least: learn a song with a lot of F chords. I chose “Let the pony run”. Strum through he chords / the song every day once. A simple downstroke on the one beat Slow down for the Mini Fs. Take all the time you need to form the Mini Fs. Strum the strings one after the other in slow motion to check if every string is ringing clearly. If a string doesn´t, don´t worry. Try one or two adjustments not more! Tehn continue through the song.If the mini F strings ring clearly strum all the strings fluently once. Then continue through the song to give the next appearing Mini F a try. Good Luck!