I use the pretty foolproof method of hosting my pic somewhere in which I have a great deal of confidence in their bandwidth, like imageshack or postimg.org, or if i'm using my phone or something is going a bit boris with my net connection, facebook, then use the img tag* with the url to embed the pic into my post - one thing to note is that imageshack hosted pics don't embed if you have edited them in any other way than cropping, so if you want to add an arrow or something by way of explanation to something you're on about, use postimg.org
*the little pic button on the edit toolbar
Edit: See, this is AF-UK and, while I'm pleased every time we get a visitor from, for eg Chile, nonetheless I'm generally posting for people with plenty of down bandwidth, so thumbnails are redundant.