There are many strategies but no sure fire way. It takes luck and timing.

You're on the right track with only UGM selected, but you need your computer to be requesting from WCG frequently. The best way to do this is have a project selected with short work units. When a unit completes, it resets the project back-off.

With just milky way you'll only be asking every few hours most times.

Ah, this thread seems to be appropriate for my "complaint", so I don't need to start a new one.
Getting Beta work surely got harder for me as it already was before - probably not only for me, also for others.
Since the regular settings require at least one project to be selected I'm not getting any beta work any more, and I have a watch notice from the board when new betas are probably been sent out. I'm trying then regularly but mostly get only a bunch of work from the selected project (which I don't want) and too much, so that the cache is full. This is very annoying and not very helpful, I think I'm trying over a year now like this. Doesn't look as if I ever get a silver badge for Beta testing...

Please, if any of the project staff is reading that, consider undo the restriction that at least 1 project needs to be selected, there is no chance to get Betas like that.

The way that I do it currently is to take in 4 FAH2 tasks with cache set at 0.2 days. Then I select FAAH since this project is throwing no tasks and set my cache to 1 day. This allows my computer to keep asking for tasks in addition to the 4 FAH2 that I am running. If there are Betas then they MAY come. Even with this babysitting, I get very few Beta tasks. Clearly the people with a large number of cores are pulling them in leaving very few for the rest of us especially with small releases which we have seen most recently in the last several Betas. Just keep trying and you will get them. Good luck.

TPCBF,

Your post is a little short of detail. Unless they disappeared off the results list more than 24 hours ago, there is still time.

The techs run a special beta result sweep script at some point(s) to give credit even for WUs for which you would not normally get any time credit. (It's a beta after all, so even errors are providing useful information. And don't forget that the validator itself needs to be tested as well, so things can go wrong with assigning good/bad result status too.)

Sometimes that sweep seems to be a short time after they switch on the validator, sometimes it doesn't seem to happen until just before they all disappear from the list. So if the result is still visible you should get the credit in the end -- just be patient.