When writing Thai letters, ALWAYS start from the location of the main loop - even in writing styles where the loop is missing, your pen will still start from that place. There are only 2 Thai letters without a loop - ก and ธ.
You will see many fonts out there that reduce or even eliminate the loop. Even so, where the loop gives the 'identity' to the letter, you will usually see a bump or a deviation that indicates where the loop should be.
To get an idea of different styles, open fonts.google.com and check out 'Thai Fonts' and look at how the loop is rendered (or not) in each font. The good thing with Google Fonts is that you'll see different handwriting style fonts too that you can model your own writing on.
Check out the first chapter of Cracking Thai Fundamentals for free here: