A lot of good advice here about slowing down. But slowing down a process you don't have a full understanding of can be fruitless as well. Sometimes it's ok just to seek help. This can be in the form of WIP's others have done or asking a nearby maker for a shop tour to see how they do it. Having another maker assess your technique and offer a new perspective can save you a lot of time and steel. Also, if you are burning through handle/guard material too fast start with hand files. Removing material more slowly and purposefully will give you more time to see what you're doing and see potential problems developing before they get away from you. Additionally, build or buy a disc sander when you have the funds. Variable speed if you can swing it. Disc sanders are very effective at flattening bevels and tangs, tapered or straight.