sorry for the short response earlier... I was out and about..
Here are a couple of things to consider when doing a project like this:
1) Freeze and thaw can be a serious issue with tiles on poured concrete slabs.
Is this slab on the ground or raised?
2) The proper type of thinset used is extremely important in outdoor installs.
3) Cement grouts (fortified)can accept moisture up to 21%. This means there is the distict possibility of freeze thaw failures. As someone mentioned earlier, a PENETRATING sealer ( SOLVENT BASED ONLY) is a fairly good addition to this procedure and will usually cut the moisture absorption rates in half.
The ability to absorb moisture also means stains. Not a big issue if a dark grout is used, but is a serious pain in the with light grout colours ( whether cement or grout is used). Just take a look at all the light grout in kitchens and hall ways that have been installed the last 10 years...
4) Epoxy grout is not mixed with cement and water. Depending on the brand, there may be sand or there may be silica sand and two part epoxy liquids. *( silica sand is preferrable as it is pure colour)
The MOISTURE ABSORPTION RATE of Epoxy grout is less than one half of one percent ! This is why it is the preferred grout used in water situations ( indoors or out) Handymen and the average tiler do not like to use epoxy grouts because they "think" it is tougher to use and they assume that it will be more costly to use. If the job fails, how much does that cost? Does the client want consistent colour with less moisture absorption?( see stains and mold and or algae`)
The new generation epoxy grouts ( in the past 5 years) are easy to work with if you can follow directions and don't work in too large of an area when u are just starting out. ( mix half batches until you get the hang of it.)
5) When I work outdoors, Pools and decks, I only grout in the morning and preferably in the shade if at all possible.
6) A common mistake of DIY installs is not sealing up the perimeters so that moisture can't penetrate the thinset there.
7) Do NOT install the tiles tight to the house or any other immovable wall. You want at least a 1/8th inch gap to allow for expansion and contraction so that you don't come home one day and find cracked tiles or tiles popped right out and laying on the grass.
Overall, don;t be afraid to try this Solopaddler. Just work in small batches untill u get the hang of it. Your focus and talent with your fishing skills are transferrable and you will enjoy your new patio for years to come.
If you have any questions, don't hesitate to contact me.