The best approach is to inject your tissue of interest with AAV2 or AAV5 adenovirus.

Thanks a lot, as some literature say electroporation after injection, in case of AAV2 or AAV5 should i go to electroporation? or direct injection is sufficient for reaching into the target cells within the tissue. Need guidance please @Anton Lennikov

It is highly dependent on the target tissue. The easiest is to design the AAV5 (or order the design) with the overexpression protein of your choice and simply inject it into the target tissue. Yes indeed you can use electroporation, but it doesn't work with every tissue. I know people even injected plasmids with lipofectamine directly into tissue with successful results. Highly depending on what are you trying to do and how strict your ethical committee is.

Thanks a lot sir, i am planning to see the effect of a gene in intramuscular fat in sheep.