The easiest suggestion is not to download programs from LW. Most of them are either infected or are available as freeware.
I have downloaded several programs from LW, and luckily my McAfee antivirus software caught all of the viruses.
Try searching for a program to see if it is available as freeware first. Then, you can get an idea what size the program should be in LW. Many of the viruses in LW are a lot smaller than the real program would be.
Organize your search results by size. If you see different program names with the exact same file size, then you are most likely looking at junk.
I never download .exe files anymore. Consider adding .exe to your filter. Only go for .rar files, so you can scan them before you open them.
Good Luck