You've gotten excellent advice so far that I totally agree with . I also use Flying Dutchman blades and highly recommend them. mike has an excellent website and is a very helpful person when it comes to blades. Super nice guy to talk to :eusa_dancI do go as low as #1 and even #2/0 when doing delicate work but I'm primarily a #3 or #5 as well. I use reverse tooth blades as mentioned by Scott almost exclusively to minimize sanding. Spirals are a good tool to have in the old arsenal and a huge benefit when doing portrait style work . They take some getting used to , but once it " clicks " you'll wonder how you ever did without them. FD sells an " easy " spiral that is quite nice to work with. For practice, try cutting out the alphabet on some 1/4" scrap . With spirals you sacrifice some of the " crispness" of your cuts and your sharp corners, plus they create a lot of "fuzzies" on the backside. These can be removed with a propane torch ....carefully ,
before you apply any finish :BangHead: or almost completely eliminated by using a piece of cereal box or other thin cardboard glued to the back of your wood .
Almost all flat blades cut on a right-hand bias due to the fact that they have a slight burr on the right hand side from the manufacturing process. You can compensate for this by sitting slightly to the right when cutting . With a little practice you will find yourself following the straight lines more accurately, but straight lines are still a major pain on a scroll saw :-(.
I also use 1/8th for ornaments and stack cut 4 to 6 at a time. This also helps keep the blade under control. I personally do not use spirals for ornaments because of the problem with " fuzzies "
this was cut in 1/8 with a #3 blade in a stack of 6
This was my own design and cut in 1/8 with a #1 in a stack of 6
Feed rate and pressure are also important. It is very easy to use the " death grip " method when pushing the wood and this can actually flex the blade to the side causing a beveled cut and more difficulty controlling the blade
Sorry for the long post but you asked a question I actually know something about .....something that will rarely happen in other sections of this forum I am sure ! :-D
hope this helps , feel free to write me with any other questions. I'm not an expert scroller by a long shot but I have figured a couple of things out in the last 2 years :-D