as you can see, this topic has been done to death and most of it you can disregard cos we have ample sunlight here. all you need to do is first, read the manual. it covers the times it takes to move from one level to the next. then just leave it on a sunny window sill or better still, somewhere in direct sun.
a couple days of full sun should get you pretty close to a full tank (i have no idea where ppl are getting WEEKS from for less than half a charge)
dont worry about it getting too hot, itll get just as hot on your arm lying in the sun at the beach, if it gets REALLY hot, the lcd may black out but thats completely normal and is detailed in the manual (you really should read it). leaving it on the dash of your car for extended periods is a no no tho.
the main thing to remember is, just cos its not 100% full doesnt mean its the end of the world, just top it up whenever you can and try not to let it run low too often. dont end up being one of those ppl that incessantly obsess over their G, the whole point of them is that theyre worry free.
oh and read the damn manual