To try and eliminate tangles try using around 80% of your shot at the base of your waggler and start placing the remainder of your shot at just over half depth going down towards the hook (going down in ever decreasing distances if several shot need to be used) so that it doesn't cause tangles in flight during the cast.
(See diagram below which shows a couple of common standard shotting patterns for shallowish swims of around 5ft-ish or less.
It will also help if you feather your line just before your float lands.
This shotting setup gives you a single main casting weight (the bulk shot at the base of the float) which helps stabilise the setup in flight. If you put a larger weight at the hook end you will have two casting points instead of one and it will a) minimise the casting distance and b) have the possibility of tangling in flight as the weight at the hook end will start to tangle around the float as it flies through the air.
After landing this setup will allow the first weight (at mid depth) to settle with the smaller weights below it sinking slightly slower behind it and giving a more natural descent.
If you want to fish tight up against lilies or other obstacles then don't feather your line as it lands and this will allow the hook length (which will be flying behind the float) to land behind the float so you should then have your float tight up to the obstacle with your hook sinking below it.
Whereas If you were feathering your line as your float started to land then your hooklength would start flying ahead of your float and be caught up in the obstacle.
I hope this is of some use to you.
Keith