Well if you want to be on the safe side you could just use 1 part tea tree oil to 3 parts water (filtered, if you can). It also seems like it would work well with aloe vera gel, although you'd have to make sure there aren't any harmful preservatives in it. People have said good things about Fruit of the Earth.

TTO will dissolve in many other products, like any anti-acne lotion you already like, or in any plain lotion like Cetaphil, but the smell will be very strong if you use it at more than a few drops. Mix test batches in a shotglass, so you don't overwhelm a whole bottle of lotion, and you can easily decide whether the aroma is ok or not..

People say it will sting at first if you mix it at 10% or more, but most people can tolerate higher concentrations after a while, even up to 50% but that seems to be way too much to me, unless someone is trying to treat against demodex motes. A typical blend of essential oils in lotion is diluted to 2% or usually much less.

Another oil you might like is Holy Basil, also called Tulsi oil. It has a clove/cinammon smell that goes down to a nice clean smell in 20 minutes. One drop will give a nice smell to 100 ml of lotion or Aloe Vera. Three drops is too much in 100 ml, IMO, for example.

Most essential oils will cause Aloe Vera to oxidize (turn brown) so make small test batch to see what happens with TTO. Leave it out on the counter for a day and then see if it oxidized -- even a little bit of brown is too much. If you use Aloe Vera, it should be kept in the refrigerator because at room temps, even without any oils added, it begins to oxidize in about 3 weeks.

My skin is too sensitive to use it without diluting, so I use 100ml water with 7-8 drops of tea tree, but this could probably be different for you depending on your skin. I've also been using a tree tree gel from Thursday Plantation which is amazing.

I dilute it with honey!