Prosthetics good enough to fool people into thinking they are real skin is possible but extremely difficult thus expensive because you'd be hiring an experienced makeup special effects artist.
This includes making a life cast of your face since prosthetics need to be sculpted on an exact copy of your face for them to sit precisely on your features so they move correctly along with the skin and muscles underneath.
They have to be applied with invisible edges and painted to look like real skin, something that takes a tremendous amount of skill and experience. You need a makeup artist on set to do touchups and glue down edges that come loose before you interact with people. This takes years of study and a certain amount of talent.
You can use some traditional stage techniques (Corson's Guide to Stage Makeup) to do some subtle contouring and shift the color of your skin. This needs to be carried down your neck past your collar line and on your hands and wrists.
The easiest ways to achieve an effective disguise are to change the shape of your face in as many ways as possible. A mustache and beard disguises your upper lip and chin, a wig of a different color with a hairstyle that is very different from yours helps you look different. Wearing glasses (or contacts if you always wear glasses) makes a difference. Thinning the eyebrows or making them bushier helps as wet as a subtle scar but it would have to be executed flawlessly.
Many years ago I was hired to disguise a woman as a man and get her past three people who knew her by appearance. I did not have time to do a life cast, sculpt, mold and cast custom prosthetics so I used the methods described here. It worked and she had considerable financial resources, so she considered my fee a worthwhile investment.
Placing inserts or arch supports in your shoes will give you a different gait. Shoulder pads or a little padding around the midsection can help to change your body shape. Fashion radically different from what you would normally wear is needed. You are creating a character, not just holding underneath a bunch of stuff.
It takes a considerable amount of acting chops to change the tone of your voice, speech patterns and accent enough to fool people. The woman mentioned above managed by speaking no more than a few words the entire night, doing a lot of nodding and smiling.
Colored contacts would help a tremendous amount but these are fairly expensive if you get both quality ones that are fitted correctly by an optometrist. Do not buy inexpensive cosplay/Halloween lenses since these are often low quality and can cause infections, corneal irritation or scarring and vision problems that may be permanent.
